Multi-module arterial spin labeling magnetic resonance angiography method, device and equipment

Abstract

The invention relates to the technical field of medical imaging, in particular to a multi-module arterial spin labeling magnetic resonance angiography method, device and equipment, and the method comprises the steps: entering a contrast stage in a magnetic resonance angiography period, applying a contrast multi-module pre-pulse to a target, and after a first delay time, executing a contrast stage; applying a three-dimensional damaged gradient echo sequence to a target, and collecting a magnetic resonance signal in a contrast stage; entering a marking stage after the contrast stage is ended, then applying a marking multi-module pre-pulse to the target, and after a second delay time, acquiring a magnetic resonance signal of the marking stage in the contrast stage; and after the marking stage is finished, entering a next magnetic resonance angiography period, and reconstructing a blood vessel image of the target according to the magnetic resonance signals of the contrast stage and the marking stage acquired in a plurality of periods. Therefore, the problems of insufficient intracranial blood marking, low marking efficiency, long marked blood transfer time and the like in related technologies are solved.

Description

Technical Field

[0001] This application relates to the field of medical imaging technology, and particularly to a multi-module arterial spin labeling magnetic resonance angiography method, device, and equipment. Background Art

[0002] ASL (Arterial Spin Labeling) is a completely non-invasive MRI (Magnetic Resonance Imaging) technology. By using radiofrequency pulses to invert or saturate the magnetization of arterial blood, the labeled blood is used as an endogenous diffusion tracer. ASL was initially used to obtain perfusion images and non-invasively quantify blood flow. After a PLD (Post-Labeling Delay) of more than 1.5 seconds, the labeled blood enters the downstream capillaries and tissues along with the blood flow. The ASL technology can also be applied to MRA (Magnetic Resonance Angiography). By combining the ASL prepulse with multiple excitation high-resolution data acquisitions and using a short PLD, image acquisition is performed when the labeled blood is still in the large blood vessels. This technology has many advantages, including non-invasiveness, high temporal and spatial resolutions, and imaging flexibility, and has important value in clinical applications. It can be used to evaluate cerebrovascular diseases such as aneurysms and vascular stenoses.

[0003] As Figure 1 shown, the main components of the ASL angiography sequence include a prepulse module and a signal acquisition module. The prepulse module includes two conditions: Label and Control. The labeled prepulse applies specific radiofrequency pulses to invert or saturate the blood flowing into the brain, while the control prepulse does not produce an inversion or saturation effect on the blood. As Figure 2 shown, the ASL acquires two types of images: labeled and control images. The labeled image is the image obtained after blood labeling, which contains the labeled spin signals and can reflect the blood flow in the cerebrovascular vessels. The control image is the image obtained without labeling, which is used as a baseline to help evaluate the changes in the labeled image. ASL eliminates static tissue and background signal noise by subtracting the labeled image from the control image to obtain vascular visualization. The effect of ASL is affected by the post-labeling delay time and the transport time from the labeling position to the distal blood vessels. A short post-labeling delay time does not allow the labeled blood to be transported to the distal blood vessels, resulting in incomplete vascular visualization; while a long post-labeling delay time will cause enhanced T1 decay, thereby reducing the signal-to-noise ratio, and the proximal blood vessels may be filled with unlabeled blood, resulting in non-visualization. Summary of the Invention

[0004] The present application provides a multi-module arterial spin labeling magnetic resonance angiography method, apparatus, and device to address issues such as insufficient intracranial blood labeling, low labeling efficiency, and poor imaging of distal small blood vessels in related technologies.

[0005] In a first aspect of the present application, a multi-module arterial spin labeling magnetic resonance angiography method is provided, including the following steps: within a magnetic resonance angiography cycle, first enter a control phase, and apply a control multi-module pre-pulse to the target. Among them, the multi-module pre-pulse includes a velocity-selective arterial spin labeling pre-pulse and a spatial-selective arterial spin labeling pre-pulse, and label the internal blood flow and external blood flow of the target based on the velocity-selective arterial spin labeling pre-pulse and the spatial-selective arterial spin labeling pre-pulse; after the application of the control multi-module pre-pulse to the target ends, after a first delay time, apply a three-dimensional spoiled gradient echo sequence to the target for the first time to acquire magnetic resonance signals in the control phase; after the control phase ends, enter a labeling phase, apply a labeling multi-module pre-pulse to the target, and after the application of the labeling multi-module pre-pulse to the target ends, after a second delay time, apply a three-dimensional spoiled gradient echo sequence to the target for the second time to acquire magnetic resonance signals in the labeling phase; after the labeling phase ends, enter the next magnetic resonance angiography cycle, and reconstruct the vascular image of the target according to the magnetic resonance signals in the control phase and the magnetic resonance signals in the labeling phase acquired within multiple magnetic resonance angiography cycles.

[0006] Optionally, modify the non-slice-selective pulse of the velocity-selective arterial spin labeling pre-pulse into a slice-selective velocity-selective pre-pulse, and apply corresponding slice selection gradients and phase compensation gradients. After the slice-selective velocity-selective pre-pulse and the spatial-selective arterial spin labeling pre-pulse are combined, they produce a synergistic effect to label the internal blood flow and external blood flow of the target respectively.

[0007] Optionally, the slice-selective pulse of the velocity-selective arterial spin labeling pre-pulse includes a slice-selective 90° flip-down pulse and a 90° flip-up pulse.

[0008] Optionally, the velocity-selective arterial spin labeling pre-pulse uses two hyperbolic secant adiabatic pulses as refocusing pulses.

[0009] Optionally, the spatial-selective arterial spin labeling pre-pulse uses at least one of a pseudo-continuous arterial spin labeling pre-pulse and a pulsed arterial spin labeling pre-pulse.

[0010] Optionally, a preset time duration is set between the velocity-selective arterial spin labeling pre-pulse and the spatial-selective arterial spin labeling pre-pulse.

[0011] Optionally, the internal blood flow and external blood flow of the target include the internal blood flow within the imaging region and the external blood flow outside the imaging region.

[0012] The second aspect of the present application provides a multi-module arterial spin labeling magnetic resonance angiography device, including: a labeling module, which is used to first enter a control phase during a magnetic resonance angiography cycle and apply a control multi-module pre-pulse to a target, where the multi-module pre-pulse includes a velocity-selective arterial spin labeling pre-pulse and a spatial-selective arterial spin labeling pre-pulse, and the internal blood flow and external blood flow of the target are labeled based on the velocity-selective arterial spin labeling pre-pulse and the spatial-selective arterial spin labeling pre-pulse; a first acquisition module, which is used to, after the application of the control multi-module pre-pulse to the target ends, after a first delay time, apply a three-dimensional spoiled gradient echo sequence to the target for the first time to acquire magnetic resonance signals in the control phase; a second acquisition module, which is used to enter a labeling phase after the control phase ends, apply a labeling multi-module pre-pulse to the target, and after the application of the labeling multi-module pre-pulse to the target ends, after a second delay time, apply a three-dimensional spoiled gradient echo sequence to the target for the second time to acquire magnetic resonance signals in the labeling phase; a reconstruction module, which is used to enter the next magnetic resonance angiography cycle after the labeling phase ends, and reconstruct the vascular image of the target according to the magnetic resonance signals in the control phase and the magnetic resonance signals in the labeling phase acquired in multiple magnetic resonance angiography cycles.

[0013] The third aspect of the present application provides a medical device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor executes the program to implement the multi-module arterial spin labeling magnetic resonance angiography method of the first aspect.

[0014] The fourth aspect of the present application provides a computer-readable storage medium, on which a computer program is stored, and the program is executed by a processor to be used to implement the multi-module arterial spin labeling magnetic resonance angiography method of the first aspect.

[0015] Therefore, the present application has the following beneficial effects:

[0016] In the embodiment of the present application, during a magnetic resonance angiography cycle, a control phase is entered, a control multi-module pre-pulse is applied to a target to label the internal and external blood flows of the target, after a first delay time, a three-dimensional spoiled gradient echo sequence is applied to the target to acquire magnetic resonance signals in the control phase; after the control phase ends, a labeling phase is entered, and then a labeling multi-module pre-pulse is applied to the target. After it ends, after a second delay time, similar to the control phase, magnetic resonance signals in the labeling phase are acquired; after the labeling phase ends, the next magnetic resonance angiography cycle is entered, and the vascular image of the target is reconstructed according to the magnetic resonance signals in the control phase and the magnetic resonance signals in the labeling phase acquired in multiple cycles. The total amount of labeled blood is large, the average labeling efficiency is high, and the transit time of the labeled blood is short. Thus, problems such as insufficient intracranial blood labeling, low labeling efficiency, and long transit time of the labeled blood in the related art are solved.

[0017] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0018] The above-mentioned and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description of the embodiments in conjunction with the drawings, where:

[0019] Figure 1 It is a schematic diagram of an ASL vascular imaging sequence;

[0020] Figure 2 It is a schematic diagram of two types of images, labeled and control, acquired by ASL;

[0021] Figure 3 It is a schematic diagram of the labeled area and the imaging area of pseudo - continuous ASL pre - pulse and pulsed ASL pre - pulse;

[0022] Figure 4 It is a flowchart of a multi - module arterial spin - labeling magnetic resonance angiography method provided according to an embodiment of the present application;

[0023] Figure 5 It is an example diagram of a multi - module arterial spin - labeling imaging sequence provided according to an embodiment of the present application;

[0024] Figure 6 It is a schematic diagram of the labeled area and the imaging area provided according to an embodiment of the present application;

[0025] Figure 7 It is a schematic diagram of the labeling effect of the blood flow inside and outside the imaging target area under the action of the multi - module arterial spin - labeling pre - pulse provided according to an embodiment of the present application;

[0026] Figure 8 It is a schematic diagram of a multi - module arterial spin - labeling magnetic resonance angiography device provided according to an embodiment of the present application;

[0027] Figure 9 It is a schematic diagram of the structure of a medical device provided according to an embodiment of the present application. Detailed Description of the Embodiments

[0028] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application, and should not be construed as limiting the present application.

[0029] In the related art, spatial-selective ASL prepulses are commonly used as tagging pulses for ASL. Currently, the commonly used tagging methods in this technology include two types: pseudo-continuous tagging and pulsed tagging. As Figure 3 shown, there are differences between the two methods in terms of the tagged spatial range and duration. PCASL (Pseudo-Continuous ASL) applies more than 1000 RF pulses at a rate of approximately 1 per millisecond, and at the same time applies a specific slice selection gradient. By controlling the phase of the RF pulses and the magnitude of the selection gradient, the flowing blood spins under the tagging conditions will be inverted when flowing through the tagging plane, while the blood remains in the non-inverted state under the control conditions. PASL (Pulsed ASL) uses a single short pulse to selectively invert the spins in a region 10-20 cm thick under the tagging conditions, and uses a single short pulse to invert the spins in a larger region under the control conditions. The blood volume tagged by PCASL is greater than that of PASL, and it has a higher signal-to-noise ratio. PASL has a higher tagging efficiency and a lower specific absorption rate compared to PCASL. However, spatial-selective ASL has obvious disadvantages: spatial-selective ASL only tags the blood outside the imaging region, and it takes a relatively long transmission time for the blood to reach the distal blood vessels from the tagging position. The tagged spins will undergo T1 relaxation, resulting in a decrease in magnetization intensity, ultimately affecting the signal intensity of the imaging. Therefore, when evaluating distal blood vessels or extremely slow blood flow, this signal loss may significantly reduce the visualization effect of the blood vessels.

[0030] VSASL (Velocity-Selective ASL) tags based on arterial blood flow velocity rather than spatial position. The velocity-selective tagging module pulse consists of a 90° tip-down and a 90° tip-up RF pulse. A bipolar gradient is applied between the two pulses under the tagging conditions. The bipolar gradient has no effect on stationary spins, but it will cause phase differences in moving spins with different flow velocities, resulting in blood signal loss. By adjusting the timing and magnitude of the bipolar gradient, signal saturation can be achieved when the blood flow velocity exceeds the set threshold. No gradient is applied under the control conditions, which will not cause obvious blood signal loss. Since the tagging position is not limited by the spatial position, velocity-selective ASL tagging can tag the blood inside and outside the imaging region at the same time, reducing the signal loss related to the transport time of the tagged blood to the distal blood vessels and enhancing the imaging effect of distal small blood vessels. This technical solution also has obvious disadvantages: compared with spatial-selective ASL, the tagging efficiency of velocity-selective ASL is lower, and it is more sensitive to field inhomogeneity, which may affect the imaging effect of large blood vessels.

[0031] In view of these drawbacks of the related art, embodiments of the present application propose a multi-module arterial spin labeling magnetic resonance angiography method, apparatus, and device, aiming to implement an imaging method with a large total amount of labeled blood, a high average labeling efficiency, and a short labeled blood transit time, which is specifically described as follows.

[0032] The multi-module arterial spin labeling magnetic resonance angiography method, apparatus, and device according to embodiments of the present application will be described below with reference to the accompanying drawings. In view of the problems in the related art such as insufficient intracranial blood labeling, low labeling efficiency, and long labeled blood transit time mentioned in the above background art, the present application provides a multi-module arterial spin labeling magnetic resonance angiography method. In this method, during the magnetic resonance angiography cycle, first enter the control phase, apply a control multi-module prepulse to the target to label the internal and external blood flows of the target; after the first application of the multi-module prepulse ends, after a first delay time, apply a three-dimensional spoiled gradient echo sequence to the target to collect the magnetic resonance signals in the control phase; after the control phase ends, enter the labeling phase, apply a labeling multi-module prepulse to the target, and after it ends, after a second delay time, similar to the control phase, collect the magnetic resonance signals in the labeling phase; after the labeling phase ends, enter the next magnetic resonance angiography cycle, and reconstruct the vascular image of the target according to the magnetic resonance signals in the control phase and the labeling phase collected in multiple cycles, with a large total amount of labeled blood, a high average labeling efficiency, and a short labeled blood transit time. Thus, the problems in the related art such as insufficient intracranial blood labeling, low labeling efficiency, and long labeled blood transit time are solved.

[0033] Specifically, Figure 4 is a schematic flow chart of a multi-module arterial spin labeling magnetic resonance angiography method provided by an embodiment of the present application.

[0034] As Figure 4 shown, the multi-module arterial spin labeling magnetic resonance angiography method includes the following steps:

[0035] In step S101, during the magnetic resonance angiography cycle, first enter the control phase, and apply a control multi-module prepulse to the target. Among them, the multi-module prepulse includes a velocity-selective arterial spin labeling prepulse and a spatial-selective arterial spin labeling prepulse, and the internal blood flow and external blood flow of the target are labeled based on the velocity-selective arterial spin labeling prepulse and the spatial-selective arterial spin labeling prepulse.

[0036] It should be noted that there are differences between the control multi-module prepulse and the labeling multi-module prepulse in the following labeling phase, which are respectively adapted to the blood labeling tasks in the two phases.

[0037] It can be understood that at the beginning of a single cycle of magnetic resonance angiography in the embodiments of the present application, the control phase is first entered, and a control multi-module pre-pulse is applied to the target. This pulse is composed of a velocity-selective arterial spin labeling pre-pulse and a spatially selective arterial spin labeling pre-pulse. The two work together to label the internal blood flow and external blood flow of the target, achieving a better blood labeling effect.

[0038] In the embodiments of the present application, the internal blood flow and external blood flow of the target include the internal blood flow within the imaging region and the external blood flow outside the imaging region.

[0039] Among them, the internal blood flow within the imaging region and the external blood flow outside the imaging region refer to the vascular blood flow within the imaging region and the vascular blood flow outside the imaging region respectively. For example, in cerebral vascular imaging, it refers to the vascular blood flow in the head region and the vascular blood flow outside the head (including the neck and chest).

[0040] In the embodiments of the present application, the non-slice-selective pulse of the velocity-selective arterial spin labeling pre-pulse is modified to a slice-selective velocity-selective pre-pulse, and the corresponding slice selection gradient and phase compensation gradient are applied. After the slice-selective velocity-selective pre-pulse is combined with the spatially selective arterial spin labeling pre-pulse, they produce a synergistic effect to label the internal blood flow and external blood flow of the target respectively.

[0041] Among them, the slice-selective velocity-selective pre-pulse selectively labels the blood not only based on the blood flow velocity but also within a specific anatomical slice; the slice selection gradient is a gradient field applied in MRI scanning to define the anatomical slice where the labeled blood is located; the phase compensation gradient is used to correct the phase shift caused by other gradients to ensure the accuracy of the labeling process.

[0042] It can be understood that in the embodiments of the present application, the non-slice-selective pulse of the velocity-selective arterial spin labeling pre-pulse is modified to a slice-selective velocity-selective pre-pulse, and the application of the corresponding slice selection gradient and phase compensation gradient is combined, which can accurately label the blood within the target region. At the same time, the slice-selective velocity-selective pre-pulse is combined with the spatially selective arterial spin labeling pre-pulse, and the two work together to efficiently label the internal blood flow and external blood flow of the target object respectively.

[0043] In the embodiments of the present application, the slice selection pulses of the velocity-selective arterial spin labeling pre-pulse include a 90° flip-down pulse and a 90° flip-up pulse for slice selection.

[0044] Among them, the function of the 90° flip-down pulse is to flip the magnetization vector from the longitudinal direction to the transverse plane, so that the magnetic moment of the spin is perpendicular to the main magnetic field B0, thereby preparing or changing the state of the spin; the function of the 90° flip-up pulse is to flip the magnetization vector from the transverse plane back to the longitudinal direction.

[0045] In the embodiments of the present application, the velocity-selective arterial spin labeling prepulse employs two hyperbolic secant adiabatic pulses as refocusing pulses.

[0046] Among them, the hyperbolic secant pulse is a special adiabatic pulse waveform with good phase characteristics, capable of achieving effective spin flips under a wide range of conditions and being insensitive to small changes in the magnetic field. The pulse shape is constructed based on the mathematical hyperbolic secant function and is usually used for selective spin excitation or inversion.

[0047] In the embodiments of the present application, the spatial-selective arterial spin labeling prepulse employs at least one of a pseudo-continuous arterial spin labeling prepulse and a pulsed arterial spin labeling prepulse.

[0048] Among them, the pseudo-continuous arterial spin labeling prepulse marks the blood in the selected slice by rapidly applying a series of short radiofrequency pulses and specific selection layer gradients. Its feature is that it can label a large amount of blood in a relatively short time, thereby providing a high signal-to-noise ratio; the pulsed arterial spin labeling prepulse uses one or more inversion pulses to simultaneously label the blood in a thick slab in a very short time and has a very high labeling efficiency.

[0049] It can be understood that the spatial-selective arterial spin labeling prepulse in the embodiments of the present application employs a pseudo-continuous arterial spin labeling prepulse and a pulsed arterial spin labeling prepulse. These two prepulse methods can be used alone or in combination to ensure that extracranial blood is effectively labeled.

[0050] In the embodiments of the present application, a preset time duration is provided between the velocity-selective arterial spin labeling prepulse and the spatial-selective arterial spin labeling prepulse.

[0051] Among them, the preset time duration is specifically set according to actual requirements and is not specifically limited herein.

[0052] It can be understood that in the embodiments of the present application, in order to prevent the mutual influence between the velocity-selective arterial spin labeling prepulse and the spatial-selective arterial spin labeling prepulse and ensure that each prepulse can complete its selective labeling task for specific blood without being interfered by the other, a time interval with a preset time duration is designed between the two.

[0053] In step S102, after the application of the control multi-module prepulse to the target is completed, after a first delay time, a three-dimensional spoiled gradient echo sequence is applied to the target for the first time, and magnetic resonance signals in the control phase are acquired.

[0054] Among them, the first delay time refers to the time period after applying the control multi-module pre-pulse, during which waiting for a period allows the labeled blood to have sufficient time to flow into the imaging area. The first delay time is specifically set according to actual requirements and is not specifically limited herein; the three-dimensional spoiled gradient echo sequence is an MRI data acquisition method that can use fast gradient echoes to collect high-resolution three-dimensional image data.

[0055] It can be understood that after the multi-module pre-pulse in the embodiment of the present application ends, after a preset first delay time, sufficient time is given for the blood to flow into the imaging area, and then the three-dimensional spoiled gradient echo sequence is directly applied, and the magnetic resonance signals in the control phase are collected.

[0056] In step S103, after the control phase ends, it enters the labeling phase, and a labeled multi-module pre-pulse is applied to the target. After the application of the labeled multi-module pre-pulse to the target ends, after a second delay time, the three-dimensional spoiled gradient echo sequence is applied to the target for the second time, and the magnetic resonance signals in the labeling phase are collected.

[0057] Among them, the second delay time refers to the time period after applying the labeled multi-module pre-pulse, during which waiting for a period allows the labeled blood to have sufficient time to flow into the imaging area. The second delay time is specifically set according to actual requirements and is not specifically limited herein.

[0058] It can be understood that after the control phase ends in the embodiment of the present application, it enters the labeling phase, and the labeled multi-module pre-pulse applicable to the labeling phase is applied to the target again. After the application is completed, after a preset second delay time, the newly labeled blood flows into the imaging area and spreads out, and then the three-dimensional spoiled gradient echo sequence is applied again to collect the magnetic resonance signals in the labeling phase.

[0059] In step S104, after the labeling phase ends, it enters the next magnetic resonance angiography cycle. According to the magnetic resonance signals in the control phase and the magnetic resonance signals in the labeling phase collected within multiple magnetic resonance angiography cycles, the vascular image of the target is reconstructed.

[0060] It can be understood that after a complete magnetic resonance angiography cycle in the embodiment of the present application ends, it will enter the next imaging cycle to repeat the above process. Each cycle includes a control phase and a labeling phase. As a series of magnetic resonance signals in the control phase and magnetic resonance signals in the labeling phase are accumulated with the execution of multiple such imaging cycles, the vascular image of the target object can be reconstructed by comparing and analyzing the magnetic resonance signals in the control phase and the magnetic resonance signals in the labeling phase within these cycles.

[0061] The multi-module arterial spin labeling magnetic resonance angiography method proposed according to the embodiments of the present application enters the control phase during the magnetic resonance angiography cycle, applies a control multi-module prepulse to the target to label the internal and external blood flows of the target; after the application of the control multi-module prepulse ends, after a first delay time, a three-dimensional spoiled gradient echo sequence is applied to the target to acquire the magnetic resonance signal in the control phase; after the control phase ends, it enters the labeling phase, and then a labeling multi-module prepulse is applied to the target. After that, after a second delay time, similar to the control phase, the magnetic resonance signal in the labeling phase is acquired; after the labeling phase ends, it enters the next magnetic resonance angiography cycle. According to the magnetic resonance signals in the control phase and the labeling phase acquired in multiple cycles, the vascular image of the target is reconstructed, achieving a large total amount of labeled blood, a high average labeling efficiency, and a short transit time of the labeled blood.

[0062] The multi-module arterial spin labeling magnetic resonance angiography method will be further described below through a specific embodiment.

[0063] The multi-module arterial spin labeling imaging sequence proposed in this embodiment is as Figure 5As shown, the sequence consists of a multi-module pre-pulse and a 3D SPGR (3D Spoiled Gradient Echo) readout. According to the actual situation and requirements, the image readout module can also use single-shot or multi-shot EPI, TFEEPI, SPIRAL, etc., which are not specifically limited here. Compared with the traditional ASL sequence using a single ASL pre-pulse, the ASL pre-pulses in the new sequence include a velocity-selective ASL pre-pulse and a spatial-selective ASL pre-pulse. The velocity-selective pre-pulse uses DRHS (Double-Refocused Hyperbolic Secant). It should be noted that in this embodiment, the DRHS is selected for the velocity-selective ASL pre-pulse, but there are also many other variants of the velocity-selective ASL pre-pulse, including DRHT (Double-Refocused Hyperbolic Tangent), BIR-8 (eight-segment B1-insensitive rotation), velocity-selective saturation or velocity-selective saturation flip based on Fourier transform, etc., which are also supported in this embodiment. In addition, this embodiment allows the use of an acceleration-selective ASL pre-pulse to replace the velocity-selective ASL pre-pulse. The spatial-selective pre-pulse uses common PCASL and FAIR (Flow-Sensitive Alternating Inversion Recovery). The velocity-selective ASL is combined with the combinations of PCASL, FAIR, PCAL, and FAIR respectively to form three multi-module pre-pulses. It should be noted that in this embodiment, the pulsed ASL pre-pulse selects FAIR, but there are also many other variants of the pulsed ASL pre-pulse, which are also supported in this embodiment. To avoid mutual influence, a short period of time is interposed between the two pre-pulses. After the pre-pulse ends, MR signal acquisition is performed after waiting for a certain labeling post-delay time.

[0064] Compared with the velocity-selective pre-pulse in the related art, the velocity-selective pre-pulse in the multi-module pre-pulse is modified to SSVS (Slab-Selective Velocity Selective), which only selectively labels the intracranial blood. For the DRHS velocity-selective pre-pulse, the non-slice-selective 90° flip-down pulse and 90° flip-up pulse it contains are changed to slice-selective pulses, and the corresponding slice-selective gradient and phase compensation gradient are applied. As Figure 6 shown, the slice-selective velocity-selective ASL pre-pulse and the spatial-selective ASL pre-pulse produce a synergistic effect after combination, respectively labeling the extracranial and intracranial blood. Figure 7Shows the effect of labeling the blood signals of internal and external blood vessels within the imaging target after combining the FAIR spatial selection prepulse and the slice selection velocity selection prepulse.

[0065] Next, a multi-module arterial spin labeling magnetic resonance angiography device according to an embodiment of the present application will be described with reference to the accompanying drawings.

[0066] Figure 8 It is a block schematic diagram of the multi-module arterial spin labeling magnetic resonance angiography device according to an embodiment of the present application.

[0067] As Figure 8 shown, the multi-module arterial spin labeling magnetic resonance angiography device 10 includes: a first labeling module 201, a first acquisition module 202, a second labeling module 203, a second acquisition module 204, and a reconstruction module 205.

[0068] Among them, the first labeling module 201 is used to first enter the control phase during the magnetic resonance angiography cycle and apply a control multi-module prepulse to the target. The multi-module prepulse includes a velocity selection arterial spin labeling prepulse and a spatial selection arterial spin labeling prepulse, and labels the internal blood flow and external blood flow of the target based on the velocity selection arterial spin labeling prepulse and the spatial selection arterial spin labeling prepulse; the first acquisition module 202 is used to apply a three-dimensional spoiled gradient echo sequence to the target for the first time after a first delay time after the control multi-module prepulse is applied to the target, and acquire the magnetic resonance signal in the control phase; the second labeling module 203 is used to enter the labeling phase after the control phase ends and apply a labeling multi-module prepulse to the target; the second acquisition module 204 is used to apply a three-dimensional spoiled gradient echo sequence to the target for the second time after a second delay time after the labeling multi-module prepulse is applied to the target, and acquire the magnetic resonance signal in the labeling phase; the reconstruction module 205 is used to enter the next magnetic resonance angiography cycle after the labeling phase ends, and reconstruct the vascular image of the target according to the magnetic resonance signals in the control phase and the magnetic resonance signals in the labeling phase acquired during multiple magnetic resonance angiography cycles.

[0069] In the embodiment of the present application, the first labeling module 201 and the second labeling module 203 are further used to modify the non-slice selection pulse of the velocity selection arterial spin labeling prepulse into a slice-selective velocity selection prepulse, and apply corresponding slice selection gradients and phase compensation gradients. After the slice-selective velocity selection prepulse and the spatial selection arterial spin labeling prepulse are combined, they produce a synergistic effect to label the internal blood flow and external blood flow of the target respectively.

[0070] In the embodiment of the present application, the slice selection pulses of the velocity selection arterial spin labeling prepulse include a slice selection 90° flip-down pulse and a 90° flip-up pulse.

[0071] In the embodiment of the present application, the velocity-selective arterial spin labeling prepulse uses two hyperbolic secant adiabatic pulses as refocusing pulses.

[0072] In the embodiment of the present application, the spatial-selective arterial spin labeling prepulse uses at least one of a pseudo-continuous arterial spin labeling prepulse and a pulsed arterial spin labeling prepulse.

[0073] In the embodiment of the present application, a preset time duration is set between the velocity-selective arterial spin labeling prepulse and the spatial-selective arterial spin labeling prepulse.

[0074] In the embodiment of the present application, the internal blood flow and external blood flow of the target include the blood flow in the vessels inside the imaging region and the blood flow in the vessels outside the imaging region.

[0075] It should be noted that the foregoing explanation of the embodiment of the multi-module arterial spin labeling magnetic resonance angiography method also applies to the multi-module arterial spin labeling magnetic resonance angiography device of this embodiment, and will not be elaborated here.

[0076] The multi-module arterial spin labeling magnetic resonance angiography device proposed according to the embodiment of the present application enters a control phase during the magnetic resonance angiography cycle, applies a control multi-module prepulse to the target to label the internal and external blood flows of the target; after the application of the control multi-module prepulse ends, after a first delay time, a three-dimensional spoiled gradient echo sequence is applied to the target to collect the magnetic resonance signals in the control phase; after the control phase ends, it enters the labeling phase, and then a labeling multi-module prepulse is applied to the target. After it ends, after a second delay time, similar to the control phase, the magnetic resonance signals in the labeling phase are collected; after the labeling phase ends, it enters the next magnetic resonance angiography cycle. According to the magnetic resonance signals in the control phase and the labeling phase collected in multiple cycles, the vascular image of the target is reconstructed, realizing a large total amount of labeled blood, a high average labeling efficiency, and a short labeled blood transit time.

[0077] Figure 9 It is a schematic structural diagram of a medical device provided by an embodiment of the present application. The medical device may include:

[0078] A memory 301, a processor 302, and a computer program stored on the memory 301 and executable on the processor 302.

[0079] When the processor 302 executes the program, it implements the multi-module arterial spin labeling magnetic resonance angiography method provided in the above embodiment.

[0080] Furthermore, the medical device further includes:

[0081] A communication interface 303 for communication between the memory 301 and the processor 302.

[0082] A memory 301 for storing a computer program that can run on a processor 302.

[0083] The memory 301 may include a high-speed RAM (Random Access Memory) memory, and may also include a non-volatile memory, such as at least one disk memory.

[0084] If the memory 301, the processor 302, and the communication interface 303 are implemented independently, the communication interface 303, the memory 301, and the processor 302 can be interconnected through a bus and communicate with each other. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For the sake of representation, Figure 9 only a thick line is used to represent it in the figure, but it does not mean that there is only one bus or one type of bus.

[0085] Optionally, in a specific implementation, if the memory 301, the processor 302, and the communication interface 303 are integrated on a chip, the memory 301, the processor 302, and the communication interface 303 can communicate with each other through an internal interface.

[0086] The processor 302 may be a CPU (Central Processing Unit), or an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present application.

[0087] The embodiments of the present application also provide a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the multi-module arterial spin labeling magnetic resonance angiography method as described above is implemented.

[0088] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or N embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0089] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0090] Any process or method description shown in a flowchart or described in other ways herein can be understood as representing a module, segment, or part of code including one or N executable instructions for implementing a customized logical function or process, and the scope of the preferred embodiments of this application includes additional implementations, where the functions can be executed in a manner that is not in the order shown or discussed, including in a substantially simultaneous manner according to the involved functions or in the reverse order, which should be understood by those skilled in the art to which the embodiments of this application belong.

[0091] It should be understood that each part of this application can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, the steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware as in another embodiment, any one or a combination of the following well-known technologies in the art can be used: discrete logic circuits with logic gate circuits for implementing logical functions on data signals, application-specific integrated circuits with appropriate combinational logic gate circuits, programmable gate arrays, field-programmable gate arrays, etc.

[0092] Those of ordinary skill in the art of this technology can understand that all or part of the steps carried by the method for implementing the above embodiments can be completed by instructing relevant hardware through a program, and the above program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0093] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A multi-module arterial spin labeling magnetic resonance angiography method, characterized in that: The following steps are involved: In a magnetic resonance angiography cycle, a control phase is firstly entered, and a control multi-module pre-pulse is applied to the target for the first time, wherein the multi-module pre-pulse includes a velocity-selective arterial spin labeling pre-pulse and a space-selective arterial spin labeling pre-pulse, and the internal blood flow and the external blood flow of the target are labeled based on the velocity-selective arterial spin labeling pre-pulse and the space-selective arterial spin labeling pre-pulse; After the control multi-module pre-pulse is applied to the target, a three-dimensional destructive gradient echo sequence is applied to the target for the first time after a first delay time to collect magnetic resonance signals in the control phase; After the control phase is finished, the marking phase is entered, a marking multi-module pre-pulse is applied to the target, and after the marking multi-module pre-pulse is applied to the target, a three-dimensional destructive gradient echo sequence is applied to the target for the second time after a second delay time, to collect magnetic resonance signals in the marking phase; After the marking phase is finished, the next magnetic resonance angiography cycle is entered, and the vascular image of the target is reconstructed according to the magnetic resonance signals of the control phase and the magnetic resonance signals of the marking phase acquired in multiple magnetic resonance angiography cycles.

2. The multi-module arterial spin labeling magnetic resonance angiography method according to claim 1, characterized in that: The non-slice selective pulse of the velocity selective arterial spin labeling pre-pulse is modified into a slice selective velocity selective pre-pulse, and the corresponding slice selective gradient and phase compensation gradient are applied. The slice selective velocity selective pre-pulse is combined with the spatially selective arterial spin labeling pre-pulse to produce a synergistic effect to respectively label the internal blood flow and external blood flow of the target.

3. The multi-module arterial spin labeling magnetic resonance angiography method according to claim 2, characterized in that: The slice-selective pulse of the velocity-selective arterial spin labeling pre-pulse includes a slice-selective 90° flip-down pulse and a 90° flip-up pulse.

4. The multi-module arterial spin labeling magnetic resonance angiography method according to claim 1, characterized in that: The velocity selective arterial spin labeling pre-pulse uses two hyperbolic secant adiabatic pulses as refocusing pulses.

5. The multi-module arterial spin labeling magnetic resonance angiography method according to claim 1, characterized in that: The spatially selective arterial spin labeling pre-pulse adopts at least one of a pseudo-continuous arterial spin labeling pre-pulse and a pulsed arterial spin labeling pre-pulse.

6. The multi-module arterial spin labeling magnetic resonance angiography method according to claim 1, characterized in that: The speed-selective arterial spin labeling pre-pulse and the space-selective arterial spin labeling pre-pulse are separated by a preset time length.

7. The multi-module arterial spin labeling magnetic resonance angiography method according to claim 1, characterized in that: The internal blood flow and the external blood flow of the target include the internal blood flow of the imaging area and the external blood flow of the imaging area.

8. A multi-module arterial spin labeling magnetic resonance angiography device, characterized in that: include: A first labeling module is used to enter a control phase within a magnetic resonance angiography cycle, and apply a control multi-module pre-pulse to the target, wherein the multi-module pre-pulse includes a velocity-selective arterial spin labeling pre-pulse and a space-selective arterial spin labeling pre-pulse, and label the internal blood flow and the external blood flow of the target based on the velocity-selective arterial spin labeling pre-pulse and the space-selective arterial spin labeling pre-pulse; A first acquisition module is used for applying a three-dimensional destructive gradient echo sequence to the target for the first time after a first delay time has elapsed after the control multi-module pre-pulse is applied to the target, so as to acquire a magnetic resonance signal of the control phase; A second marking module is used to enter the marking phase after the control phase ends, and apply a control multi-module pre-pulse to the target; A second acquisition module is used for applying a three-dimensional damaging gradient echo sequence to the target for the second time after a second delay time has passed after the application of the marking multi-module pre-pulse to the target, so as to acquire the magnetic resonance signal of the marking stage; The reconstruction module is used to enter the next magnetic resonance angiography cycle after the marking phase ends, and reconstruct the vascular image of the target according to the magnetic resonance signals of the control phase and the magnetic resonance signals of the marking phase collected in multiple magnetic resonance angiography cycles.

9. A medical device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the multi-module arterial spin labeling magnetic resonance angiography method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: When the computer program or instruction is executed, the multi-module arterial spin labeling magnetic resonance angiography method according to any one of claims 1 to 7 is implemented.

Images