Inflow enhancement effect-based cerebral cortex puncturing small blood vessel magnetic resonance imaging method and device

Abstract

The invention discloses a cerebral cortex penetrator small blood vessel magnetic resonance imaging method based on an inflow enhancement effect. The method comprises the following steps: modeling a penetrator small blood vessel to generate a blood vessel TOF (Time of Flight) image; calculating the blood vessel-grey matter contrast ratio of the blood vessel TOF image under different FAs and different TRs, and optimizing the FAs and the TRs according to the blood vessel-tissue contrast ratio; obtaining a structural image of the in-vivo brain tissue, performing cortex reconstruction, and calculating an angle of a surface normal of each cortex vertex relative to the B0 field to obtain a cortex angle graph; adjusting a single-layer blood vessel scanning plane angle according to the cortex angle diagram; and according to the optimized FA and TR and the single-layer blood vessel scanning plane angle determined in the step S4, carrying out magnetic resonance imaging on the cerebral cortex perforation small blood vessel. The invention further discloses a cerebral cortex puncturing small blood vessel magnetic resonance imaging device based on the inflow enhancement effect. According to the method and the device, magnetic resonance imaging of the cerebral cortex perforation small blood vessel can be realized under the non-invasive and contrast-agent-free conditions.

Description

Technical Field

[0001] This invention belongs to the field of magnetic resonance imaging technology, and specifically relates to a method and device for magnetic resonance imaging of small perforating vessels in the cerebral cortex based on the inflow enhancement effect. Background Technology

[0002] The cerebral vascular system is a hierarchical, tree-like structure, including large-scale anterior, middle, and posterior cerebral arteries and the great cerebral vein, mesoscale piacular vessels, and cortical perforators. A network of cerebral arteries covering the cortical surface then descends vertically into the cortex via arterioles. Oxygenated hemoglobin, after passing through the network of capillaries originating from these arterioles, participates in brain function through neurovascular coupling mechanisms. Subsequently, deoxygenated blood is collected in ascending venules and vertically returns to the tree-like network of surface venous vessels and the venous network at the base of the skull. Therefore, perforators are crucial nodes for blood flow into and out of the cerebral cortex, playing a vital role in normal functions such as oxygen supply and metabolism during neural activity, as well as in abnormal brain pathological activities in neurological and psychiatric disorders. Imaging perforators is of great significance in clinical and basic scientific research.

[0003] Time-of-flight (TOF) magnetic resonance angiography of the brain, utilizing the inflow enhancement effect, has been widely applied in clinical and basic scientific research (e.g., Chinese patent CN106821381A discloses a dual-echo sampling method for three-dimensional time-of-flight angiography; and Chinese patent CN113313728A discloses intracranial artery segmentation using three-dimensional time-of-flight magnetic resonance angiography images). However, since the inflow enhancement effect depends on blood flow velocity, vessel size, and the position of the scanning plane relative to the vessel, current methods are mainly for macroscopic vessels (greater than 100 micrometers) with high flow velocities and large vessel diameters. There remains a technological gap in imaging small, slow-flowing cortical perforating vessels with complex cortical orientations (complex folded morphology).

[0004] The use of iron-containing contrast agents in magnetic resonance cerebral angiography has been applied in basic scientific research (e.g., the paper with doi 10.1002 / nbm.2885 uses monocrystalline iron oxide nanoparticles (MION) for cortical vessel localization; and the paper with doi https: / / doi.org / 10.7554 / eLife.99940.4 uses ferumoxytol nanoparticles for imaging the whole-brain vascular network). However, because the contrast agent causes T2* signal attenuation in arteries and veins, it is difficult to distinguish between them in images. Furthermore, the phase decoupling of vascular signals caused by iron results in a "blooming effect" outside the vessels, leading to a large error in estimating vessel diameter using this method.

[0005] Therefore, there is still a technical gap in how to image cortical perforator vessels and distinguish between perforator arterioles and veins under non-invasive, harmless, and contrast agent-free conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a magnetic resonance imaging method for small perforating vessels in the cerebral cortex based on the inflow enhancement effect, which can realize magnetic resonance imaging of small perforating vessels in the cerebral cortex under non-invasive and contrast agent-free conditions.

[0007] This invention provides the following technical solution: A magnetic resonance imaging method for small perforating vessels in the cerebral cortex based on inflow enhancement effect, the method comprising: S1. Model the perforating small blood vessels to generate vascular TOF images; S2. Calculate the vessel-gray matter contrast of the vessel TOF image under different flip angles (FA) and different repetition times (TR), and optimize FA and TR based on the vessel-tissue contrast. S3. Obtain structural images of in vivo brain tissue and perform cortical reconstruction. Calculate the angle of the surface normal of each cortical vertex relative to the B0 field to obtain a cortical angle map. S4. Adjust the angle of the single-layer blood vessel scanning plane according to the cortical angle diagram; S5. Perform magnetic resonance imaging of small perforating vessels in the cerebral cortex based on the FA and TR optimized in S2 and the single-layer vascular scanning plane angle determined in S4.

[0008] In S1, prior physiological parameters of brain tissue and magnetic resonance acquisition parameters are used as inputs. The perforating small blood vessels are modeled using the fluid Bloch equation to simulate and generate a time-of-flight (TOF) image of the blood vessels with flowing blood at the center and stationary gray matter around them. The final vascular TOF image is obtained by simulating and taking into account the actual blood flow characteristics and some volume effects. The prior physiological parameters of brain tissue include: T1 value of gray matter, T2 value of gray matter, T1 value of blood, T2 value of blood, blood flow velocity of perforating blood vessels, and diameter of perforating blood vessels. The magnetic resonance acquisition parameters include: flip angle FA and repetition time TR.

[0009] The blood flow velocity of the perforator is 1-50 mm / s, the diameter of the perforator is 10-80 μm, the flip angle FA is between 10 and 90 degrees, and the repetition time TR is between 10 and 200 ms.

[0010] In S2, the intensity difference of blood and tissue signals under different flow velocities is plotted based on the contrast-to-noise ratio (CNR) of TR and FA, and the magnetic resonance acquisition parameters FA and TR corresponding to different blood vessel flow velocities and blood vessel diameters are optimized by evaluating CNR.

[0011] The optimal flow rate (TR) is determined by averaging the vessel-gray matter contrast at different inversion angles. Then, under the optimized TR, the optimal flow rate (FA) for obtaining the vessel-gray matter contrast at the target flow rate is determined.

[0012] In S3, brain structural data is acquired by preparing a fast gradient echo sequence with magnetization, structural imaging is obtained, and cortical reconstruction is performed to generate a cortical surface with triangle vertices as units. The cortical surface includes the white matter / gray matter surface and the gray matter / cerebrospinal fluid surface. The angle of the surface normal of each cortical vertex relative to the B0 field is calculated by selecting the triangle vertices of the gray matter / cerebrospinal fluid surface to obtain the cortical angle map.

[0013] In S4, the angle between the surface normal of the single-layer blood vessel scanning plane and the B0 field is adjusted to zero, and the angle of the cortical angle map of the region of interest is obtained.

[0014] Because the flow velocity in small vessels is relatively slow, imaging needs to maximize the inflow enhancement effect. The angle between the TOF imaging plane and the vessel plays a crucial role in the inflow enhancement effect. If the perforating vessel is parallel to the scanning plane, the blood flow takes longer to pass through the scanning plane, reducing the inflow enhancement effect. Therefore, the scanning plane should be as perpendicular to the perforating vessel as possible to reduce the time the blood flow takes to pass through the imaging plane, thereby maximizing the inflow enhancement effect. Based on the prior information that the perforating vessel is perpendicular to the cortical plane, this method uses the surface normal of the cortical vertex as an estimate of the perforating vessel angle, thus assisting in planning the vascular imaging scanning plane.

[0015] Furthermore, this invention utilizes a 7T magnetic resonance imaging system to acquire structural imaging of in vivo brain tissue and magnetic resonance images of small perforating vessels in the cerebral cortex.

[0016] The present invention also provides a magnetic resonance imaging device for small perforating vessels in the cerebral cortex based on the inflow enhancement effect, the device comprising: The data simulation module models small perforating vessels and generates TOF images of the vessels. The parameter optimization module calculates the vessel-gray matter contrast of the vessel TOF image under different flip angles (FA) and different repetition times (TR), and optimizes FA and TR based on the vessel-tissue contrast. The cortical orientation calculation module acquires structural images of in vivo brain tissue and performs cortical reconstruction, and calculates the angle of the surface normal of each cortical vertex relative to the B0 field to obtain a cortical angle map. The single-layer vascular scanning planar imaging module adjusts the angle of the single-layer vascular scanning plane according to the cortical angle map, and then generates magnetic resonance images of small perforating vessels in the cerebral cortex based on the optimized FA and TR and the angle of the single-layer vascular scanning plane.

[0017] The specific execution methods of each module correspond to the magnetic resonance imaging method of small perforating vessels in the cerebral cortex based on the inflow enhancement effect, and will not be elaborated here.

[0018] The present invention also provides a magnetic resonance imaging device for small perforating vessels of the cerebral cortex based on the inflow enhancement effect, comprising a memory and one or more processors, wherein the memory stores executable code, and the one or more processors execute the executable code to implement the above-mentioned magnetic resonance imaging method for small perforating vessels of the cerebral cortex based on the inflow enhancement effect.

[0019] The present invention also provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, is used to implement the above-described method for magnetic resonance imaging of small perforating vessels in the cerebral cortex based on the inflow enhancement effect.

[0020] The magnetic resonance imaging method and device for small perforating vessels in the cerebral cortex based on the inflow enhancement effect provided by this invention are applicable to primates.

[0021] Compared with the prior art, the present invention has the following beneficial effects: Compared with traditional magnetic resonance angiography, this invention provides a non-invasive and contrast agent-free imaging method for cortical perforator microvessels (perforator vessels in complex morphology within the cortex) that are small in size, have slow flow rates, and whose vessels follow complex folds in the cortex. The method provided by this invention can achieve results superior to those of contrast agent imaging and can reduce the estimation error of blood vessel diameter; The method provided by this invention is characterized by precision and flexibility. It can visualize micron-sized cortical perforator vessels and flexibly adjust the scanning field of view to achieve cortical perforator vessel imaging across brain regions. The magnetic resonance imaging method and device for perforating microvessels in the cerebral cortex provided by this invention have the characteristics of being modular and automated. Attached Figure Description

[0022] Figure 1 A flowchart of a magnetic resonance imaging method for small perforating vessels in the cerebral cortex based on inflow enhancement effect; Figure 2 The selection of parameters for image simulation-guided cortical perforator vessel imaging in this embodiment; Figure 3 This is an example of a single-layer scanning plane angle plan guided by cortical angle. Figure 4 This example illustrates transcerebral cortical perforator vessel imaging. Figure 5 Imaging of perforating vessels in the sulcus endothelial region of the brain; Figure 6 This example is a comparison with invasive contrast agent angiography. Detailed Implementation

[0023] The specific embodiments of the present invention will now be described with reference to the accompanying drawings, so that those skilled in the art can better understand the present invention.

[0024] Example 1 like Figure 1 As shown, the magnetic resonance imaging method for small perforating vessels in the cerebral cortex based on inflow enhancement effect provided by the present invention specifically includes: (1) Modeling perforating small vessels to generate vascular TOF images, specifically including S1 and S2: S1. Input prior physiological parameters of brain tissue, including: T1 and T2 values ​​of gray matter, T1 and T2 values ​​of blood, blood flow velocity, diameter of blood vessel walls, etc. In this embodiment, the range of blood flow velocity and diameter of cortical perforator vessels is estimated based on existing anatomical and optical imaging reports: the blood flow velocity range of intracortical perforator vessels is 1-50 mm / s, and the vessel diameter range is 10-80 μm. In this embodiment, based on the report from 7T MRI, the arterial longitudinal relaxation time T 1,blood = 2100 ms, lateral relaxation time T2 * ,blood = 69 ms; gray matter longitudinal relaxation time T1 ,GM = 2010 ms; Lateral relaxation time T2 * ,GM= 59 ms.

[0025] In this embodiment, based on the common range of FA and TR in TOF imaging, FA is set between 10 and 90 degrees (in increments of 10 degrees), and TR is set between 10 and 200 ms (in increments of 10 ms).

[0026] S2, Multi-parameter inflow enhancement effect image simulation S2-1. Model perforating small blood vessels to generate TOF images of blood vessels with flowing blood at the center and stationary gray matter surrounding them. After inputting the parameters from S1 into the program, the Bloch equation is used to solve for the magnetization of the flowing spin within the blood vessel and the magnetization of the stationary gray matter tissue, generating a simulated image with flowing blood at the center and stationary gray matter tissue surrounding it: First, it is assumed that a single-layer two-dimensional scanning plane perpendicular to the blood vessel has been obtained. Then, the TOF image is modeled using the fluid Bloch equation, taking into account the blood flow velocity of the perforator, the diameter of the inner wall of the blood vessel, the magnetic resonance acquisition parameters, the real blood flow characteristics and some volume effects, to simulate the TOF image of the perforator.

[0027] In image simulation, the transverse relaxation vector of the flowing blood is solved by formula (1): (1) Among them, T2 * Transverse relaxation time of digital arteries (T2) * ,blood ), α This is the flip angle (FA), and TE represents the echo time. Mz This represents the longitudinal relaxation vector of blood at position v×TR before the nth excitation pulse, from n=1 to nRF (radio frequency pulse). Mz Then it can be recursively defined by formula (2): (2) in, M 0 For balancing the magnetization vector, TR is the repetition time (TR).

[0028] The transverse relaxation vector of the stationary gray matter is solved by formula (3): (3) Among them, T * 2, tissue T represents the transverse relaxation time of gray matter brain tissue. 1,tissue This refers to the longitudinal relaxation time of gray matter brain tissue.

[0029] Ultimately, this was achieved by separately applying voxels to blood flow and quiescent gray matter tissue. M xy The value is used to obtain a simulated TOF image.

[0030] S2-2. Taking into account the actual blood flow characteristics and some volume effects, the final vascular TOF image is obtained through simulation. Considering the laminar flow pattern of blood flow in blood vessels, the blood flow velocity included in the calculation is integrated into the laminar flow pattern by formula (4): (4) in, D It is the diameter of the inner wall of the blood vessel. v 0 The average blood flow velocity is represented by x, and x and y represent the horizontal and vertical coordinates of the intravascular voxels, respectively. Due to the small diameter of cortical perforator vessels and the limited imaging resolution, this image simulation considers some volume effects. We first generated an ultra-high resolution image 32 times higher than the final simulated TOF image, and then downsampled the image to the actual acquisition resolution to obtain the final simulated TOF image.

[0031] Time-of-flow (TOF) signals obtained from blood vessels are easily affected by the local volume effect of surrounding tissues.

[0032] In this embodiment, the acquisition parameters used in the image simulation are: scan layer thickness = 1 mm; voxel size = 64 μm × 64 μm; TE = 9 ms; an ideal square scan layer is assumed in the simulation: FOV = 19.26 mm × 19.26 mm; gray matter signal-to-noise ratio = 14.

[0033] In this embodiment, each TOF simulated image contains a blood vessel located at the center, with blood flow velocities of 1, 3, 5, 10, 20, 30, 40 and 50 mm / s, and blood vessel diameters ranging from 10 to 80 μm in increments of 10 μm; FA is between 10 and 90 degrees (in increments of 10 degrees), and TR is between 10 and 200 ms (in increments of 10 ms).

[0034] (2) Calculate the vessel-gray matter contrast of the vascular TOF image under different flip angles (FA) and different repetition times (TR), and optimize the scanning parameters FA and TR based on the vessel-tissue contrast, specifically including S3 and S4: S3. Comparison of image contrast of multi-parameter inflow enhancement effect: Using the final vascular TOF image simulated in S2 as the input of S3, the influence of image acquisition parameters on vascular contrast is evaluated for vascular vessels with specific flow velocities and inner wall diameters.

[0035] S4. Calculate the contrast-to-noise ratio (CNR) of blood vessels and tissues under different parameters, and solve for the FA and TR that generate the highest contrast: To determine the optimal TR and FA for TOF contrast, this method calculates the vessel-tissue contrast of each set of simulated images and plots the contrast-to-noise ratio (CNR) of the intensity difference between blood and tissue signals at different flow rates with respect to TR and FA, referring to formula (5). Based on the contrast evaluation, the optimal scanning parameters for the target flow rate and vessel diameter can be selected, for example: TR = 60 ms, FA = 60°.

[0036] (5) in, S vessel The signal intensity of blood vessels, S tissue The signal intensity of gray matter. σ background This represents the standard deviation of the background noise.

[0037] (3) Obtain structural images of in vivo brain tissue and perform cortical reconstruction, and calculate the angle of the surface normal of each cortical vertex relative to the B0 field to obtain a cortical angle map; specifically including S5-S7: S5. Acquiring brain structural data through magnetization prepared-rapid-gradient-echo (MPRAGE) sequence: Structural images were acquired using a 7T MRI scanner and MPRAGE sequence for reconstruction of the macaque cerebral cortex and localization of the visual field during vascular scanning.

[0038] S6. Perform cortical reconstruction on the obtained structural image data. According to the FreeSurfer cortical surface reconstruction process, based on the MPRAGE structural items obtained from the scan, generate cortical surfaces with triangle vertices as units, including white matter / gray matter surfaces and gray matter / cerebrospinal fluid surfaces.

[0039] S7. Obtain the surface normal of each cortical vertex. Then, using the angle between the surface normal of the cortical vertex on the gray matter / cerebrospinal fluid surface and the B0 field, generate a "cortical angle map" to show the corresponding positional relationship between the single-layer scanning plane of the region of interest and the entire cerebral cortex.

[0040] (4) Adjust the angle of the single-layer vascular scanning plane according to the cortical angle diagram; specifically including S8-S9: S8. Perform single-layer vascular TOF imaging: Based on structural imaging, place the scanning field of view (FOV) of the single-layer vascular scanning plane in the region of interest.

[0041] S9. Select the imaging center, calculate the relative angle between the surface normal of the single-layer blood vessel scanning plane and the B0 field, and combine the angle of the structural image data relative to the B0 field ("cortical angle map") to automatically adjust the surface normal of the single-layer blood vessel scanning plane and the optimal point of interest in the "cortical angle map" to zero.

[0042] The single-layer vascular scanning plan provided by this invention aims to make the scanning plane as tangent as possible to the vertex of the cortical surface in the region of interest, i.e., the normal of the scanning plane is parallel to the normal of the cortical vertex. After initially determining and adjusting the single-layer vascular scanning plane, the optimal cortical surface vertex of the region of interest is selected on the scanning interface. Subsequently, the program automatically calculates the angle between the scanning plane and the cortical surface vertex, making the angle zero to maximize the surface inflow enhancement effect.

[0043] (5) Magnetic resonance imaging of small perforating vessels in the cerebral cortex is performed based on the optimized FA and TR in S2 and the single-layer vascular scanning plane angle determined in S4; specifically including S10: S10. Single-layer vascular imaging data acquisition: Data acquisition is performed based on the optimized FA and TR confirmed in step (2) and the scanning angle confirmed in step (4). Other scanning parameters are generally fixed: FOV = 66 mm × 66 mm, matrix size = 1024 × 1024, achieving 64×64 μm. 2 High in-plane spatial resolution, slicethickness = 1 mm, bandwidth = 110 Hz / pix, TE = 9.13, 25.96, 42.79 ms (as small as possible TE), number of repetitions = 20, scan time 20 minutes 29 seconds.

[0044] Figure 2 The parameters selected for image simulation-guided cortical perforator vessel imaging in this embodiment are as follows: A. Time-of-Flight (TOF) imaging simulation of vessels and tissues; B. TOF imaging simulation of vessels with different flow velocities and diameters; C. Visualization of imaging contrast surface maps for more continuous flow velocities and diameter parameters; D. Contrast trends of vessels relative to tissues at different flow velocities under different TR parameters; E. Contrast trends of vessels relative to tissues at different flow velocities under different FA parameters; F. Experimental data obtained using different TR and FA parameters; G. Differences in vessel-gray matter tissue contrast in images acquired with different TR and FA parameters. * p<0.05; ** p<0.01; ** p<0.001.

[0045] Figure 2 The white dot in the center of image A (circled by a red dashed box) is a cross-sectional view of the simulated perforating vessels in the gray matter of the cerebral cortex, and the background is a cross-sectional view of the simulated gray matter brain tissue from magnetic resonance imaging. Figure 2 Figures B and C show that for vessels with different blood flow velocities and diameters, different vessel-gray matter contrasts can be simulated using image analysis. For perforating vessels with different flow velocities, the optimal vessel-gray matter contrast (TR) is obtained. Figure 2 D) and FA ( Figure 2 The E) parameters differ. This method first determines the optimized TR by averaging the vessel-gray matter contrast at different inversion angles, and then determines the optimal FA for obtaining the target flow velocity vessel-gray matter contrast under the optimized TR. Figure 2 The F-values ​​show significant differences in cortical perforator vessel imaging obtained with different TR and FA acquisition parameters. Comparative data show that the data acquisition parameters TR=60 and FA=60, determined through data simulation, can provide the optimal vessel-gray matter contrast. Figure 2 (G).

[0046] Figure 3 The single-layer scanning plane angle plan guided by cortical angle in this embodiment is as follows: Figure 3 In this diagram, A represents the "cortical angle diagram" showing the angle between the surface normal of the cortical vertex and the field B0. Figure 3 B in the diagram represents the angle between the normal of the single-layer scanning plane and the normal of the cortical surface. The optimal imaging position is the position with the smallest angle (blue). Figure 3 C in the text is based on ( Figure 3 In section B), the scanning plane angle setting in the angle map is used to determine the position of the region of interest located at the minimum angle between the scanning plane (light yellow) and the cortical apex (gray); Figure 3 In the image, D represents a cross-sectional view of the cortical perforating vessels obtained after scanning. The white dots in the image represent cortical perforating vessels, which show a high signal relative to the background gray matter due to the inflow enhancement effect.

[0047] Following magnetic resonance imaging (MRI), this method reconstructs the cortical surface from the MRI data into units of triangular vertices. This is used to calculate the angle of the surface normal of each cortical vertex relative to the B0 field, generating a "cortical angle map". Figure 3 (A) Subsequently, based on structural information and cortical angles, a single-layer vascular imaging plane plan is constructed, initially placing the scanning plane within the region of interest. By calculating the angle between the normal of the single-layer vascular scanning plane and the B0 field, the angle between the single-layer vascular scanning plane and the structural image "cortical angle map" is then calculated. Figure 3 In step B), the angle between the two points of interest approaches zero to increase the inflow enhancement effect in the region of interest. Finally, based on the optimal angle, the single-layer scanning plane is determined ( Figure 3(C in the image), begin scanning to obtain a single-layer vascular cross-sectional image ( Figure 3 (D in the middle).

[0048] Figure 4 Transcerebral cortical perforator vessel imaging in this embodiment: Figure 4 A and B in the diagram represent the selected layer regions guided by structural imaging (yellow boxes): these selected layer regions contain multiple brain regions, such as V1, V2, V3, V4, and LIP. Figure 4 C in the image represents the micron-scale perforator vessels in the gray matter of multiple brain regions (indicated by red circles).

[0049] Based on the scanning parameters confirmed by image simulation and the scanning plane angle calculated from the cortical angle, magnetic resonance imaging (MRI) is finally performed on the sample. Utilizing the inflow enhancement effect, a cross-sectional image of the cortical perforator vessels is obtained. This method is characterized by precision and flexibility, capable of displaying micron-sized cortical perforator vessels and allowing for flexible adjustment of the scanning field of view, enabling cortical perforator vessel imaging across brain regions. Figure 4 ).

[0050] More importantly, this method can also image areas extending into the cortical folds and sulci. For example... Figure 5 The image shown is an imaging study of perforating vessels in the sulcus endothelial region of the brain. Figure 5 In the image, A represents a single-layer vascular image (right side) obtained by selecting a slice area using structural image guidance (yellow box); the green arrows correspond to landmarks in the MPRAGE and GRE images, respectively; the image within the purple box is magnified and presented in... Figure 5 In the image, B is highlighted in red; the bright spots caused by the inflow enhancement effect represent the cross-section of the perforating artery; the dark spots caused by the T2* attenuation effect represent the cross-section of the perforating vein. Figure 5 In the figure, C represents the acquisition of samples at different times with the same scanning parameters and scanning positions, to prove that the detected bright spots have real physiological structures rather than random noise, and to show that the method has good repeatability.

[0051] like Figure 5 As shown in Figure A, placing the scanning plane in the cortical region posterior to the intraparietal sulcus (IPS) and performing single-layer vascular imaging enables imaging of cortical perforator vessels over a wide area. Further magnification of the region of interest reveals regularly arranged arterial cross-sections appearing as white bright spots due to inflow enhancement; simultaneously, small venous cross-sections appearing as dark spots due to T2* attenuation can also be detected. These results fully demonstrate the innovation and effectiveness of this method.

[0052] Figure 6 This embodiment is a technical comparison with invasive contrast agent angiography. Figure 6In this example, A represents the imaging effect, including bright spots formed by the inflow enhancement effect, representing the cross-section of the perforating artery (circled in red), and dark spots caused by the T2* attenuation effect, representing the cross-section of the perforating vein (circled in blue). Figure 6 In the diagram, B represents an image obtained using a monocrystalline iron oxide contrast agent (MION), a commonly used contrast agent in animal magnetic resonance imaging (MRI) experiments in neuroscience. This embodiment offers advantages over contrast agent-based imaging methods. First, due to the T2* attenuation of vascular signals caused by MION, arteries and veins appear as dark spots in the image, making them difficult to distinguish. Second, the phase decoupling of vascular signals caused by MION results in a "blooming effect" outside the arteries and veins, leading to a larger estimation error in vessel diameter compared to this embodiment. Finally, the harmful nature of MION contrast agents makes its clinical application in humans difficult, limiting the widespread adoption and application of this imaging method. Therefore, this embodiment achieves superior imaging results compared to contrast agent-based methods under non-invasive, contrast agent-free conditions, and reduces the estimation error in vessel diameter.

[0053] This invention also provides a magnetic resonance imaging device for small perforating vessels in the cerebral cortex based on inflow enhancement effect, including one or more processors. Executable code is stored in a memory. When the processor executes the executable code, it implements the method for reconstructing the macaque cerebral cortex for ultra-high field magnetic resonance imaging described in the above embodiments. Taking software implementation as an example, as a logical device, it is formed by the processor of any data processing device that houses the device reading the corresponding computer program instructions from non-volatile memory into memory for execution. From a hardware perspective, in addition to the processor, memory, network interface, and non-volatile memory, the data processing device in the embodiments typically includes other hardware depending on its actual function, which will not be elaborated further.

[0054] This invention also provides a computer-readable storage medium storing a program that, when executed by a processor, implements the cerebral cortical perforator small vessel magnetic resonance imaging method based on inflow enhancement effect described in the above embodiments. The computer-readable storage medium can be an internal storage unit of any data processing device as described in any of the foregoing embodiments, such as a hard disk or memory. The computer-readable storage medium can also be any data processing device, such as a plug-in hard disk, smart media card (SMC), SD card, flash memory card, etc., mounted on the device. Furthermore, the computer-readable storage medium can include both internal storage units of any data processing device and external storage devices. The computer-readable storage medium is used to store computer programs and other programs and data required by any data processing device, and can also be used to temporarily store data that has been output or will be output.

Claims

1. A magnetic resonance imaging method for small perforating vessels in the cerebral cortex based on inflow enhancement effect, characterized in that, The method includes: S1. Model the perforating small blood vessels to generate vascular TOF images; S2. Calculate the vessel-gray matter contrast of the vessel TOF image under different flip angles (FA) and different repetition times (TR), and optimize FA and TR based on the vessel-tissue contrast. S3. Obtain structural images of in vivo brain tissue and perform cortical reconstruction. Calculate the angle of the surface normal of each cortical vertex relative to the B0 field to obtain a cortical angle map. S4. Adjust the angle of the single-layer blood vessel scanning plane according to the cortical angle diagram; S5. Perform magnetic resonance imaging of small perforating vessels in the cerebral cortex based on the FA and TR optimized in S2 and the single-layer vascular scanning plane angle determined in S4.

2. The method for magnetic resonance imaging of small perforating vessels in the cerebral cortex based on inflow enhancement effect according to claim 1, characterized in that, In S1, prior physiological parameters of brain tissue and magnetic resonance acquisition parameters are used as inputs. The fluid Bloch equation is used to model perforating small blood vessels and simulate the generation of a blood vessel TOF image with flowing blood in the center and stationary gray matter in the surrounding area. The final vascular TOF image is obtained by simulating the actual blood flow characteristics and some volume effects. The prior physiological parameters of the brain tissue include: T1 value of gray matter, T2 value of gray matter, T1 value of blood, T2 value of blood, blood flow velocity of perforating vessels, and vessel diameter of perforating vessels. The magnetic resonance acquisition parameters include: flip angle FA and repetition time TR.

3. The method for magnetic resonance imaging of small perforating vessels in the cerebral cortex based on inflow enhancement effect according to claim 2, characterized in that, The blood flow velocity of the perforator is 1-50 mm / s, the diameter of the perforator is 10-80 μm, the flip angle FA is between 10 and 90 degrees, and the repetition time TR is between 10 and 200 ms.

4. The method for magnetic resonance imaging of small perforating vessels in the cerebral cortex based on inflow enhancement effect according to claim 1, characterized in that, In S2, the intensity difference of blood and tissue signals under different flow velocities is plotted based on the contrast-to-noise ratio (CNR) of TR and FA, and the magnetic resonance acquisition parameters FA and TR corresponding to different blood vessel flow velocities and blood vessel diameters are optimized by evaluating CNR.

5. The method for magnetic resonance imaging of small perforating vessels in the cerebral cortex based on inflow enhancement effect according to claim 4, characterized in that, The optimal flow rate (TR) is determined by averaging the vessel-gray matter contrast at different inversion angles. Then, under the optimized TR, the optimal flow rate (FA) for obtaining the vessel-gray matter contrast at the target flow rate is determined.

6. The method for magnetic resonance imaging of small perforating vessels in the cerebral cortex based on inflow enhancement effect according to claim 1, characterized in that, In S3, brain structural data are acquired by preparing a fast gradient echo sequence through magnetization, structural imaging is obtained and cortical reconstruction is performed, generating a cortical surface with triangle vertices as units. The cortical surface includes the white matter / gray matter surface and the gray matter / cerebrospinal fluid surface. By selecting the vertices of a triangle on the surface of gray matter / cerebrospinal fluid, the angle of the surface normal of each cortical vertex relative to the B0 field is calculated to obtain the cortical angle map.

7. The method for magnetic resonance imaging of small perforating vessels in the cerebral cortex based on inflow enhancement effect according to claim 1, characterized in that, In S4, the angle between the surface normal of the single-layer blood vessel scanning plane and the B0 field is adjusted to zero, and the angle of the cortical angle map of the region of interest is obtained.

8. A magnetic resonance imaging device for small perforating vessels in the cerebral cortex based on inflow enhancement effect, characterized in that, The device includes: The data simulation module models small perforating vessels and generates TOF images of the vessels. The parameter optimization module calculates the vessel-gray matter contrast of the vessel TOF image under different flip angles (FA) and different repetition times (TR), and optimizes FA and TR based on the vessel-tissue contrast. The cortical orientation calculation module acquires structural images of in vivo brain tissue and performs cortical reconstruction, and calculates the angle of the surface normal of each cortical vertex relative to the B0 field to obtain a cortical angle map. The single-layer vascular scanning planar imaging module adjusts the angle of the single-layer vascular scanning plane according to the cortical angle map, and then generates magnetic resonance images of small perforating vessels in the cerebral cortex based on the optimized FA and TR and the angle of the single-layer vascular scanning plane.

9. A magnetic resonance imaging device for small perforating vessels of the cerebral cortex based on inflow enhancement effect, comprising a memory and one or more processors, wherein the memory stores executable code, and the one or more processors execute the executable code to implement the magnetic resonance imaging method for small perforating vessels of the cerebral cortex based on inflow enhancement effect as described in any one of claims 17.

10. A computer-readable storage medium having a program stored thereon, which, when executed by a processor, is used to implement the magnetic resonance imaging method for small perforating vessels in the cerebral cortex based on the inflow enhancement effect as described in any one of claims 17.

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