CN116029963A

CN116029963A - Vascular reactivity evaluation method, vascular reactivity evaluation device, electronic device, and storage medium

Info

Publication number: CN116029963A
Application number: CN202111248385.XA
Authority: CN
Inventors: 周诗辉; 张丽娟; 史彩云; 蔡思琦; 邹超
Original assignee: Shenzhen Institute of Advanced Technology of CAS
Current assignee: Shenzhen Institute of Advanced Technology of CAS
Priority date: 2021-10-26
Filing date: 2021-10-26
Publication date: 2023-04-28
Also published as: WO2023070865A1

Abstract

The embodiment of the invention discloses a vascular reactivity evaluation method, a vascular reactivity evaluation device, electronic equipment and a storage medium, wherein the vascular reactivity evaluation method comprises the following steps: acquiring a first magnetic susceptibility weighted imaging of a brain region of a target object in a free breathing state and a second magnetic susceptibility weighted imaging of the target object in a breath hold state; determining a vascularity map of the brain region; determining a first oxygen uptake fraction of the target vessel in a free breathing state according to the first susceptibility weighted imaging and the vascularity profile; determining a second oxygen uptake fraction of the target vessel in the breath hold state according to the second susceptibility weighted imaging and the vascularity profile; determining an evaluation index of the vascular reactivity of the target blood vessel based on the first oxygen uptake fraction and the second oxygen uptake fraction of the target blood vessel, and evaluating the vascular reactivity of the target blood vessel based on the evaluation index. The effect of evaluating vascular reactivity simply, rapidly and accurately by oxygen uptake fractions in a free breathing state and in a breath-hold state can be achieved.

Description

Vascular reactivity evaluation method, vascular reactivity evaluation device, electronic device, and storage medium

Technical Field

The embodiment of the invention relates to the technical field of biomedicine, in particular to a vascular reactivity evaluation method, a vascular reactivity evaluation device, electronic equipment and a storage medium.

Background

The oxygen uptake fraction (oxygen extraction fraction, OEF) is a parameter reflecting the oxygen demand and utilization by brain tissue, and OEF is distributed more uniformly throughout the brain in physiological conditions and increases or decreases to varying degrees in pathological conditions. Current research is focused mainly on quantitative estimation of oxygen uptake scores and visual imaging of their distribution throughout the brain.

At present, the magnetic resonance estimation oxygen uptake fraction method is mainly based on inversion solution of different magnetic susceptibility information of different oxygenation states of hemoglobin. Deoxyhemoglobin is a strongly paramagnetic substance, and the T2 relaxation signal is significantly shortened under a magnetic field compared to oxyhemoglobin. Although the method for estimating the oxygen uptake fraction by adopting the magnetic resonance imaging method can realize noninvasive quantitative measurement, the magnetic resonance acquisition time is too long (2 minutes-10 minutes), and the blood vessel autonomous regulation function information cannot be acquired in the single oxygen supply and consumption process of the organism; although the method of sucking carbon dioxide and other gases with different proportions can simulate vascular reactions under different anoxic states, the method is only used for experimental research at present and has a plurality of limitations in clinical applicability.

Disclosure of Invention

The embodiment of the invention provides a vascular reactivity evaluation method, a vascular reactivity evaluation device, electronic equipment and a storage medium, so as to realize the effects of completing magnetic resonance oxygen uptake fraction estimation in a short time and determining vascular reactivity.

In a first aspect, an embodiment of the present invention provides a method for evaluating vascular reactivity, including:

acquiring a first magnetic susceptibility weighted imaging of a brain region of a target object in a free breathing state and a second magnetic susceptibility weighted imaging of the target object in a breath-hold state;

determining a vascularity map of the brain region;

determining a first oxygen uptake fraction of a target vessel of the brain region in a free breathing state from the first susceptibility weighted imaging and the vascularity map;

determining a second oxygen uptake fraction of a target vessel of the brain region in a breath-hold state from the second susceptibility weighted imaging and a vascularity profile;

determining an evaluation index of the vascular reactivity of a target blood vessel based on the first oxygen uptake score and the second oxygen uptake score of the target blood vessel, and evaluating the vascular reactivity of the target blood vessel based on the evaluation index.

In a second aspect, an embodiment of the present invention further provides an apparatus for evaluating vascular reactivity, including:

the magnetic susceptibility weighted imaging acquisition module is used for acquiring a first magnetic susceptibility weighted imaging of a brain region of a target object in a free breathing state and a second magnetic susceptibility weighted imaging of the target object in a breath-holding state;

a vascularity map determination module for determining a vascularity map of the brain region;

a first oxygen uptake score determination module for determining a first oxygen uptake score of a target vessel of the brain region in a free breathing state from the first susceptibility weighted imaging and the vascularity map;

a second oxygen uptake score determination module for determining a second oxygen uptake score of a target vessel of the brain region in a breath hold state from the second susceptibility weighted imaging and a vascularity profile;

and the blood vessel reactivity evaluation module is used for determining an evaluation index of the blood vessel reactivity of the target blood vessel according to the first oxygen uptake fraction and the second oxygen uptake fraction of the target blood vessel, and evaluating the blood vessel reactivity of the target blood vessel based on the evaluation index.

In a third aspect, an embodiment of the present invention further provides an electronic device, including:

one or more processors;

storage means for storing one or more programs,

the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the method for evaluating vascular reactivity provided by any embodiment of the present invention.

In a fourth aspect, an embodiment of the present invention further provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method for evaluating vascular reactivity provided by any embodiment of the present invention.

According to the technical scheme, the first magnetic susceptibility weighted imaging of the brain region of the target object in the free breathing state and the second magnetic susceptibility weighted imaging of the target object in the breath-holding state are obtained, cerebral vascular imaging in different oxygen metabolism environments can be determined, and the corresponding first quantitative magnetic susceptibility map and second quantitative magnetic susceptibility map can be further determined through the obtained first magnetic susceptibility weighted imaging and second magnetic susceptibility weighted imaging. Determining a vascularity map of the brain region, determining a first oxygen uptake fraction of a target blood vessel of the brain region in a free breathing state from the first susceptibility weighted imaging and the vascularity map; and determining a second oxygen uptake fraction of the target vessel of the brain region in a breath-hold state based on the second susceptibility weighted imaging and a vascularity profile; parameters of oxygen demand and utilization rate of the target blood vessel of the brain region of the target object are respectively determined in a free breathing state and a breath hold state; finally, an evaluation index of the vascular reactivity of the target blood vessel is determined according to the first oxygen uptake fraction and the second oxygen uptake fraction of the target blood vessel, and the vascular reactivity of the target blood vessel is evaluated based on the evaluation index. To determine a vascular response capability of the target vessel based on the first oxygen uptake score and the second oxygen uptake score. The method solves the problem that no effective method for evaluating the vascular reactivity exists at present, achieves the technical effect of evaluating the vascular reactivity simply, rapidly and accurately through oxygen uptake scores in a free breathing state and a breath-holding state, and is applicable to clinical application.

Drawings

In order to more clearly illustrate the technical solution of the exemplary embodiments of the present invention, the drawings required for describing the embodiments are briefly described below. It is obvious that the drawings presented are only drawings of some of the embodiments of the invention to be described, and not all the drawings, and that other drawings can be made according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a flow chart of a method for evaluating vascular reactivity according to an embodiment of the present invention;

FIG. 2 is a flow chart of a method for evaluating vascular reactivity according to a second embodiment of the present invention;

FIG. 3 is a schematic diagram showing an experimental procedure of a method for evaluating vascular reactivity according to a second embodiment of the present invention;

FIG. 4 is a graph showing the results of the blood vessel reactivity oxygen uptake score in the method for evaluating blood vessel reactivity according to the second embodiment of the present invention;

fig. 5 is a schematic structural diagram of an apparatus for evaluating vascular reactivity according to a third embodiment of the present invention;

fig. 6 is a schematic structural diagram of an electronic device according to a fourth embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.

It should be further noted that, for convenience of description, only some, but not all of the matters related to the present invention are shown in the accompanying drawings. Before discussing exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although a flowchart depicts operations (or steps) as a sequential process, many of the operations can be performed in parallel, concurrently, or at the same time. Furthermore, the order of the operations may be rearranged. The process may be terminated when its operations are completed, but may have additional steps not included in the figures. The processes may correspond to methods, functions, procedures, subroutines, and the like.

Example 1

Fig. 1 is a schematic flow chart of a method for evaluating vascular reactivity according to an embodiment of the present invention, where the method may be applied to determining vascular reactivity, and the method may be performed by a device for evaluating vascular reactivity, which may be implemented by software and/or hardware, and may be configured in a terminal and/or a server to implement the method for evaluating vascular reactivity according to the embodiment of the present invention.

As shown in fig. 1, the method of this embodiment may specifically include:

s110, acquiring first magnetic susceptibility weighted imaging of a brain region of a target object in a free breathing state and second magnetic susceptibility weighted imaging of the target object in a breath hold state.

Susceptibility weighted imaging (Susceptibility Weighted Imaging, SWI) is a novel imaging technique that uses the differences in susceptibility of different tissues to generate image contrast.

The target object is understood as an object to be acquired by magnetic resonance method for weighted imaging of susceptibility of brain region. The brain region may be understood as the whole brain region of the target object.

In the embodiment of the present invention, the first susceptibility weighted imaging may be understood as susceptibility weighted imaging acquired by a target subject in a Free respiratory (FB) state, and may be expressed as SWI ₁ . The second susceptibility weighted imaging can be understood as the targetSusceptibility weighted imaging of a subject in the Breath-Hold (BH) state, which can be expressed as SWI ₂ 。

Specifically, in order to avoid the influence of the instrument on the classification result, the data of all the target objects participating in the study adopts the magnetic resonance imaging (Magnetic Resonance Imaging, MRI) instrument of the same model and the same scanning sequence to carry out resting state scanning on the head of the target objects. Then, under the free breathing state of the target object, acquiring first magnetic susceptibility weighted imaging data SWI of the brain region of the target object ₁ . Acquiring second susceptibility weighted imaging data SWI of brain region of target object in breath-hold state of target object ₂ 。

Among them, vascular reactivity is understood as the ability of a blood vessel to contract or relax under the influence of various influencing factors, and can effectively reflect the vascular regulating ability.

Alternatively, SWI-based ₁ The brain data of the target object is collected as brain region magnetic susceptibility reference data of vascular reactivity. Optionally based on SWI ₂ And acquiring brain region data of the target object as blood vessel reactivity brain region magnetic susceptibility data.

Optionally, a time difference between the acquisition time of the first susceptibility weighted imaging and the acquisition time of the second susceptibility weighted imaging is within a preset difference range, and parameters of a scanning sequence adopted by the first susceptibility weighted imaging and the second susceptibility weighted imaging are the same.

Specifically, the time difference between the acquisition time of the first susceptibility weighted imaging and the acquisition time of the second susceptibility weighted imaging is within a preset difference range, in other words, the smaller the time difference between the acquisition time of the first susceptibility weighted imaging and the acquisition time of the second susceptibility weighted imaging, the better.

Specifically, the first susceptibility weighted imaging acquisition time is shorter, and the average maximum breath holding time of the target object is taken as the setting time of the first susceptibility weighted imaging and the second susceptibility weighted imaging in consideration of the variability of the breath holding time of the target object. In the embodiment of the invention, in order to ensure that the data in the free breathing state is accurate and is not influenced by breath-holding, the susceptibility weighted imaging in the free breathing state can be acquired preferentially, and then the susceptibility weighted imaging in the breath-holding state is acquired. Since the susceptibility weighted imaging in the free breathing state is acquired first, the acquisition time of the first susceptibility weighted imaging may be set first, for example, the time in the free breathing state of the target object is set within 30s, and then the acquisition time of the second susceptibility weighted imaging in the breath-hold state is controlled to be approximately the same as the acquisition time of the first susceptibility weighted imaging, for example, the preset difference range may be set within ±2 s.

The parameters of the scanning sequence adopted by the first magnetic susceptibility weighted imaging and the second magnetic susceptibility weighted imaging are the same, so that the influence caused by the difference of acquisition equipment or the difference of acquisition parameters in the acquisition process of the magnetic susceptibility weighted imaging can be reduced to the maximum extent.

S120, determining a vascularity map of the brain region.

The vascular distribution map is understood to be a map of the distribution position and shape of blood vessels in the brain region, and the condition of the blood vessels, such as the thickness, branches, distribution positions and connection relations between the blood vessels and the respective blood vessels, can be clearly seen through the vascular distribution map. There are various methods that can be used to determine the vascularity map of the brain region, for example, by deep learning algorithms, multi-modal fusion algorithms, image segmentation or morphological processing.

Specifically, taking the case of determining the blood vessel distribution of the brain region based on a deep learning algorithm as an example, magnetic resonance blood vessel imaging can be performed on the brain region first, then gray values of the obtained magnetic resonance blood vessel imaging are preprocessed, the region of interest is determined according to a preset threshold, and then the blood vessel region in the brain region is extracted according to the region of interest. Dividing a blood vessel region into a plurality of partial images, selecting a certain fixed blood vessel region for marking according to a 3DUNet network in a deep learning algorithm, randomly selecting a plurality of partial regions by taking the region as a base point to obtain a partial blood vessel segmentation result, and then splicing all the partial regions to obtain an integral blood vessel distribution map.

The method for image segmentation is also used for determining a vessel distribution map, marking key points of vessels in magnetic resonance vessel imaging, determining geometric feature points of vessels in brain regions, finding out matched feature point pairs, carrying out serialization subtraction images on brain region images through the relation between the matched feature point pairs, extracting a set of feature point sets in the serialization subtraction images, carrying out local position adjustment on feature points of vessel edges in the subtraction images, moving the feature points of the vessel edges into the vessels by using gray values, and carrying out image segmentation based on region growth and self-adaptive thresholds to obtain the vessel distribution map of the brain region.

There are various methods for determining the vascularity map of the brain region, which are not limited thereto and may be determined according to actual needs.

Optionally, the determining a vascularity map of the brain region includes: acquiring a third susceptibility weighted imaging of the brain region of the target object in a free breathing state; determining a third quantitative susceptibility map corresponding to the third susceptibility weighted imaging; determining a vascularity map of the brain region from the prior knowledge template of the brain region, the third susceptibility weighted imaging, and the third quantitative susceptibility map.

The acquisition time of the third magnetic susceptibility weighted imaging is longer than that of the first magnetic susceptibility weighted imaging.

The prior knowledge template can be understood as knowledge information which can be known based on prior knowledge, and in the embodiment of the invention, each voxel of a brain region has the probability of blood vessels, and the prior knowledge template can represent a probability template that each voxel in susceptibility weighted imaging is a venous blood vessel.

Specifically, the probability that each voxel of brain tissue is a vessel can be known from a priori knowledge templates of brain regions. And acquiring third magnetic susceptibility weighted imaging of the target object under the free breathing state, and acquiring venous blood vessel segmentation of the whole brain based on high-resolution data of the third magnetic susceptibility weighted imaging. And then processing according to the third magnetic susceptibility weighted imaging to obtain a third quantitative magnetic susceptibility map, and further determining a vascular distribution map of the brain region of the target object according to the third quantitative magnetic susceptibility map to obtain the whole cerebral vascular network distribution. Therefore, the three aspects of the prior knowledge template, the third magnetic susceptibility weighted imaging and the third quantitative magnetic susceptibility map are subjected to Gaussian mixture weighted summation, so that the venous vascular distribution map of the brain region can be obtained, the distribution of venous blood vessels of the brain region can be accurately judged, and the complete segmentation of the venous blood vessels is facilitated.

Optionally, the determining the third quantitative susceptibility map corresponding to the third susceptibility weighted imaging includes: generating a brain mask image based on the raw amplitude image of the third susceptibility weighted imaging; determining an intra-brain susceptibility weighted imaging of the brain region of the third susceptibility weighted imaging corresponding to an intra-brain region; performing phase resolution processing and background field removal processing on the original phase image of the weighted imaging of the brain magnetic susceptibility to obtain a target phase image; and calculating the magnetic susceptibility distribution of each voxel in the brain internal region according to the amplitude priori information of the brain mask image, the target phase image and the least square method, and reconstructing a third quantitative magnetic susceptibility map.

The mask image is understood as an image filtering template, and is generally constructed by a morphological method and is used for extracting a region of interest of a brain region of a target object. Susceptibility weighted imaging can be understood as acquiring data based on a gradient echo sequence, and performing special data processing and image reconstruction to form a magnetic resonance imaging technology sensitive to the susceptibility of a substance. In the embodiment of the invention, the intra-brain susceptibility weighted imaging can be understood as the acquired data obtained by carrying out susceptibility weighted imaging on the brain region of the target object. The original phase image can be understood as a magnetic resonance image obtained by scanning a brain region of a target object by using a magnetic resonance imaging technology, wherein the obtained phase data difference of different protons forms an image contrast, and the image contrast magnetic resonance image can be used for reflecting the original phase information of the different protons in a relaxation process. The method of processing the solution phase may be linear or nonlinear, and a least square solution phase processing method or a weighted least square solution phase processing method may be employed, for example.

Specifically, in the quantitative susceptibility imaging process, the acquired data includes two parts of information of an internal brain region and an external brain region, the internal brain region needs to be reserved as an interested region, and the interested region is finally presented in the quantitative susceptibility result, so that a non-interested region of the brain region of the target object needs to be filtered in the quantitative susceptibility process. There are various ways to determine the region of interest of the brain region of the target object, for example, there may be a method based on gray histogram threshold image segmentation, region dilation morphology method, amplitude image segmentation, edge image segmentation, wavelet transformation image segmentation, region growing image segmentation, and specific theory image segmentation, and the method may be used to divide the region of interest in the image by using these image segmentation methods. When the region of interest of the image is determined, the method for generating the brain mask image based on the original amplitude image of the third susceptibility weighted imaging in the free breathing state of the target object can obtain the intra-brain susceptibility weighted imaging corresponding to the intra-brain region of the brain region, filter out the non-region of interest such as the skull and the like, and provide brain boundary information for the image data with better quality in the next step.

And determining the weighted imaging of the brain magnetic susceptibility corresponding to the brain internal region according to the constructed brain mask image, performing phase solving processing and background field removing processing on the original phase image of the weighted imaging of the brain magnetic susceptibility to obtain a target phase image, and finally solving the quantitative magnetic susceptibility of the brain image information by combining the prior probability of the magnetic susceptibility and a least square method, and reconstructing a third quantitative magnetic susceptibility map.

Similarly, under the free breathing state of the target object, the same operation is carried out based on the third magnetic susceptibility weighted image, and a third quantitative magnetic susceptibility map is reconstructed; and under the condition that the target object holds breath, carrying out the same operation based on the second magnetic susceptibility weighted image, and reconstructing a second quantitative magnetic susceptibility map.

Optionally, the performing a dephasing process on the original phase image of the weighted imaging of the susceptibility in the brain includes: and carrying out regional phase winding estimation according to the phase information and the scanning time of a plurality of voxels of the original phase image of the weighted imaging of the cerebral magnetic susceptibility, and carrying out inverse solution on the aliasing phase based on the estimation result to obtain the real phase information of the weighted imaging of the cerebral magnetic susceptibility.

Specifically, since the magnetic resonance scans the brain region for a long time, the phase image of the susceptibility weighted imaging has an image phase aliasing phenomenon, so that the image needs to be subjected to a dephasing process to be resolved into time information and space information. And then carrying out regional phase winding estimation by combining the phase information of a plurality of voxels and the scanning time, and carrying out inverse solution on the aliasing phase to obtain real phase information. Alternatively, when the phase separation processing is performed on the image, the processing is started in the region with less phase aliasing in the phase image imaged by the susceptibility weighting, and the processing is gradually performed to the region with more phase aliasing.

S130, determining a first oxygen uptake fraction of a target blood vessel of the brain region in a free breathing state according to the first susceptibility weighted imaging and the vascularity map.

The target vessel may be understood as a venous vessel of a brain region of the target subject. The acquisition mode of the target blood vessel comprises, but is not limited to, an image segmentation method, a corrosion expansion algorithm, a seed growth method, a region filling method, a mathematical morphology method, a watershed method or a pattern recognition method and the like. The first oxygen uptake fraction may be understood as a parameter of the demand and utilization of oxygen by the target blood vessels of the brain region of the target subject in the free breathing state. The oxygen uptake fraction can be determined in various ways, for example, noninvasive oxygen uptake fraction measurement can be performed based on an asymmetric spin echo rapid imaging technology, quantitative measurement can be performed by using a T2 relaxation spin labeling imaging technology, a gas-free task vascular reactivity measurement mode can be simulated, the proportion of oxyhemoglobin and deoxyhemoglobin in a target blood vessel is measured through an intermittent breath-holding state and a free breathing state, and the oxygen uptake fraction in the breath-holding state and the free breathing state processes is calculated respectively by combining the time of the state change process.

Specifically, a third susceptibility weighted imaging of the brain region of the target object in the free breathing state can be obtained, a third quantitative susceptibility map corresponding to the third susceptibility weighted imaging is determined, and the brain region of the target object is scanned by adopting a magnetic resonance instrument of the same model and the same scanning sequence for the acquisition of the third susceptibility weighted imaging and the first susceptibility weighted imaging, wherein the scanning frequency is not limited, and can be one time or multiple times. In order to ensure the validity of the acquired data and the accuracy of the oxygen uptake fraction calculation, the acquisition time of the third susceptibility weighted imaging can be made longer than that of the first susceptibility weighted imaging in the acquisition process. The acquisition time of the third susceptibility weighted imaging is longer than the acquisition time of the first susceptibility weighted imaging, for example, the acquisition time may be set to 2-10 minutes.

In the free breathing state of the target object, the brain region of the target object is subjected to resting scanning through a magnetic resonance instrument, the brain region of the target object is scanned by adopting a 3D gradient echo sequence by utilizing the magnetic sensitivity difference among different tissues, and special data processing and image reconstruction are performed on the magnetic resonance scanning image on the basis of the scanning result, so that a first susceptibility weighted imaging and a third susceptibility weighted imaging are obtained. And determining a first oxygen uptake fraction of the target blood vessel in the free breathing state according to the first magnetic susceptibility weighted imaging and the vascular distribution map and the tissue magnetic susceptibility characteristics corresponding to different tissues.

And S140, determining a second oxygen uptake fraction of the target blood vessel of the brain region in a breath-hold state according to the second susceptibility weighted imaging and the vascularity map.

The image acquisition parameters of the second magnetic susceptibility weighted imaging are the same as those of the first magnetic susceptibility weighted imaging, and the same type of magnetic resonance instrument, the same scanning sequence and the same scanning parameters are adopted, so that the acquisition of the second magnetic susceptibility weighted imaging is different from the first magnetic susceptibility weighted imaging, and the brain region of the target object is scanned in a state that the target object holds breath. The second oxygen uptake fraction may be understood as a parameter of the demand and utilization of oxygen by the target subject in breath-hold conditions.

Specifically, the brain region of the target object is subjected to resting scanning through a magnetic resonance instrument in a breath-hold state of the target object, the brain region of the target object is scanned through a 3D gradient echo sequence by utilizing magnetic sensitivity differences among different tissues, special data processing and image reconstruction are carried out on a magnetic resonance scanning image on the basis, a second susceptibility weighted imaging is obtained, and then a second oxygen uptake fraction of a target blood vessel of the brain region in the breath-hold state is determined according to the second susceptibility weighted imaging and a vascularity map.

S150, determining an evaluation index of the vascular reactivity of the target blood vessel according to the first oxygen uptake fraction and the second oxygen uptake fraction of the target blood vessel, and evaluating the vascular reactivity of the target blood vessel based on the evaluation index.

Among them, vascular reactivity is understood as the ability of a blood vessel to contract or relax under the influence of various vascular influencing factors, and can effectively reflect the vascular regulating ability. The evaluation index of the vascular reactivity may include that the target blood vessel inhales carbon dioxide in two states of a free breathing state and a breath hold state, the oxygen uptake fraction of the target blood vessel in different states is tested, the difference is used as the evaluation index of the vascular reactivity, and the vascular reactivity of the target blood vessel is evaluated based on the evaluation index.

Illustratively, after inhalation of carbon dioxide in the target subject's free breathing state, the flow velocity in the target vessel is significantly faster; under the excessive ventilation state of the target object, the average blood flow velocity in the target blood vessel is obviously slowed down, and after 20-30 s of excessive ventilation, the blood flow velocity in the target blood vessel is gradually stable without obvious change; in the breath-hold state of the target object, the blood flow in the target blood vessel is obviously accelerated along with the increase of the breath-hold time of the target object, and the blood flow in the target blood vessel is gradually stabilized after the breath-hold state of the target object exceeds 30 s. Therefore, the rate of increase in the blood flow velocity or the breath-hold index in the target blood vessel in three states can be used as an index for evaluating the blood vessel reactivity, wherein it is most convenient to use the reaction of the target blood vessel in the breath-hold state of the target subject as an index for evaluating the blood vessel reactivity of the target blood vessel in the brain region.

Specifically, a first oxygen uptake fraction of a target vessel of the brain region in a free breathing state is determined from the first and third susceptibility weighted imaging. A second oxygen uptake fraction of the target vessel of the brain region in a breath-hold state is determined from the second and third susceptibility weighted imaging. An evaluation index of the vascular reactivity of the target blood vessel is determined based on the first oxygen uptake score and the second oxygen uptake score of the target blood vessel, and the vascular reactivity of the target blood vessel is evaluated based on the evaluation index.

Optionally, the determining the evaluation index of the vascular reactivity of the target blood vessel according to the first oxygen uptake fraction and the second oxygen uptake fraction of the target blood vessel includes: for each voxel of a target blood vessel, calculating a score difference value of the first oxygen uptake score and the second oxygen uptake score, and determining an evaluation index of the blood vessel reactivity of the target blood vessel according to the score difference value.

The intravascular voxels are understood to be the spatial units of the human body, which are represented by a pixel in the image, and also to be the smallest geometrical units which can be resolved in the magnetic resonance effects, a voxel containing at least one blood cell.

Specifically, the first oxygen uptake score and the second oxygen uptake score in each voxel can be calculated for each voxel in the target blood vessel in the magnetic resonance image, then the score difference value of the two oxygen uptake scores corresponding to each voxel is calculated, and the evaluation index of the blood vessel reactivity of the target blood vessel can be determined according to the score difference value corresponding to each voxel. For example, the method may specifically include calculating score differences of the first oxygen uptake score and the second oxygen uptake score of the plurality of voxels in the target blood vessel, respectively, then performing weighted average on the score differences corresponding to the plurality of voxels, and taking the score differences after the weighted average as an evaluation index of the vascular reactivity of the target blood vessel. The method may further include the steps of weighting and summing first oxygen uptake scores of the plurality of voxels in the target blood vessel, then averaging to obtain a first oxygen uptake score average value, weighting and summing second oxygen uptake scores of the plurality of voxels in the target blood vessel, then averaging to obtain a second oxygen uptake score average value, and further using a score difference value between the first oxygen uptake score average value and the second oxygen uptake score average value as an evaluation index of the blood vessel reactivity of the target blood vessel.

Optionally, the first susceptibility weighted imaging, the second susceptibility weighted imaging, and the third susceptibility weighted imaging are registered.

In particular, registration may be understood as registering the first susceptibility weighted imaging, the second susceptibility weighted imaging, and the third susceptibility weighted imaging to correct pixels characterizing the same tissue in the three sets of data to the same location to accommodate the needs of data analysis. For example, the rotation target angle can be obtained by susceptibility weighted imaging.

Illustratively, in SWI ₂ For reference, SWI ₁ And SWI ₂ Standard feature statistics and linear fits were performed to correct both sets of data to the same location. In SWI ₂ For reference, constraint SWI ₃ And SWI ₂ And correcting the two groups of data to the same position by mutual information entropy of the gray values.

According to the technical scheme, the first magnetic susceptibility weighted imaging of the brain region of the target object in the free breathing state and the second magnetic susceptibility weighted imaging of the target object in the breath-holding state are obtained, and the corresponding first quantitative magnetic susceptibility map and second quantitative magnetic susceptibility map can be further determined through the obtained first magnetic susceptibility weighted imaging and second magnetic susceptibility weighted imaging. Determining a vascularity map of the brain region, determining a first oxygen uptake fraction of a target blood vessel of the brain region in a free breathing state from the first susceptibility weighted imaging and the vascularity map; and determining a second oxygen uptake fraction of the target vessel of the brain region in a breath-hold state based on the second susceptibility weighted imaging and a vascularity profile; parameters of oxygen demand and utilization rate of the target blood vessel of the brain region of the target object are respectively determined in a free breathing state and a breath hold state; finally, an evaluation index of the vascular reactivity of the target blood vessel is determined according to the first oxygen uptake fraction and the second oxygen uptake fraction of the target blood vessel, and the vascular reactivity of the target blood vessel is evaluated based on the evaluation index. To determine a vascular response capability of the target vessel based on the first oxygen uptake score and the second oxygen uptake score. The method solves the problem that no effective method for evaluating the vascular reactivity exists at present, achieves the technical effect of evaluating the vascular reactivity simply, rapidly and accurately through oxygen uptake scores in a free breathing state and a breath-holding state, and is applicable to clinical application.

Example two

Fig. 2 is a flow chart of a method for evaluating vascular reactivity according to a second embodiment of the present invention, where, based on any one of the optional technical solutions of the second embodiment of the present invention, optionally, the determining the first oxygen uptake fraction of the brain region in the free breathing state according to the first susceptibility weighted imaging and the vascularity profile includes: determining a first quantitative susceptibility map corresponding to the first susceptibility weighted imaging; and calculating a first oxygen uptake score of each voxel in the target blood vessel according to the quantitative magnetic susceptibility of each voxel in the first quantitative magnetic susceptibility map and a pre-established relationship between the quantitative magnetic susceptibility and the oxygen uptake score aiming at each voxel of the target blood vessel in the blood vessel distribution map.

Specifically, the method of the present embodiment may include:

s210, acquiring first magnetic susceptibility weighted imaging of a brain region of a target object in a free breathing state and second magnetic susceptibility weighted imaging of the target object in a breath hold state.

S220, determining a vascularity map of the brain region.

S230, determining a first quantitative susceptibility map corresponding to the first susceptibility weighted imaging.

The quantitative susceptibility map can be understood as a map reconstructed by a susceptibility inversion technology, and quantitative susceptibility imaging is a technology for quantitatively measuring the magnetization characteristics of tissues in a magnetic resonance technology, so that the susceptibility caused by the change of the blood oxygen saturation in the tissues can be effectively quantitatively analyzed. The first quantitative susceptibility map may be understood as a first quantitative susceptibility map corresponding to the first susceptibility weighted imaging acquired by the quantitative magnetization imaging technology under the free breathing state of the target object.

Specifically, a first quantitative magnetic susceptibility solution is performed on a brain region of a target object in a free breathing state, and a first quantitative magnetic susceptibility map corresponding to the first magnetic susceptibility weighted imaging is obtained.

Optionally, the performing a dephasing process and a background field removing process on the original phase image of the weighted imaging of the brain magnetic susceptibility includes: and removing the background field of the original phase image of the weighted imaging of the cerebral magnetic susceptibility based on the characteristic that the orthogonal product of the unit dipole field of the cerebral internal area of the cerebral area and the unit dipole field of any background field is smaller than or equal to a preset threshold.

Wherein in other words, it may be determined whether the brain interior region unit dipole field of the brain region and any background field unit dipole field orthogonal product is less than or equal to a preset threshold value, which may be, for example, a value of 0 or close to 0. The background field is understood to be caused by non-uniformity of the magnetization source and the main magnetic field outside the region of interest, and the presence of the background field affects the calculation of the susceptibility of the region of interest, so that the background field components need to be filtered out before the susceptibility is calculated.

Specifically, in the embodiment of the invention, a dipole field projection method is adopted to remove the background field, and the characteristic that the orthogonal product of the dipole background field of the non-interested region and the local dipole field of the interested region is close to 0 in the interested region is utilized to remove the background field, so that the influence of the background field on the interested region is reduced. The determination mode close to 0 may be whether the orthogonal product of the dipole background field of the non-region of interest and the local dipole field of the region of interest is within a preset error range. In other words, the difference between the quadrature product and 0 is within a predetermined error range.

S240, calculating a first oxygen uptake score of each voxel in the target blood vessel according to the quantitative magnetic susceptibility of each voxel in the first quantitative magnetic susceptibility map and the relation between the pre-established quantitative magnetic susceptibility and the oxygen uptake score aiming at each voxel of the target blood vessel in the blood vessel distribution map.

Specifically, after determining a vessel distribution map according to a priori knowledge template of a brain region, a third magnetic susceptibility weighted imaging and a third quantitative magnetic susceptibility map, calculating a first oxygen uptake fraction of each voxel in a target vessel according to the quantitative magnetic susceptibility of each voxel in the quantitative magnetic susceptibility map and a relation between the quantitative magnetic susceptibility and the oxygen uptake fraction, which are established in advance, for each voxel of the vessel in the vessel distribution map.

Optionally, the relationship between the quantitative susceptibility and the oxygen uptake fraction is determined based on the following formula:

wherein OEF is the oxygen uptake fraction of the voxel; Δχ _vein-CSF ＝χ _vein -χ _CSF ，χ _vein Quantitative susceptibility, χ, of venous vessels in the quantitative susceptibility profile _CSF Quantitative susceptibility to cerebrospinal fluid in the anterior lateral ventricle region; Δχ _vein-CSF Indicating venous vessel and cerebrospinal fluid susceptibility differences; Δχ _deoxy Magnetic susceptibility differences of oxygenated and deoxygenated erythrocytes per unit hematocrit; Δχ _oxy-CSF ＝χ _oxy -χ _CSF ，Δχ _oxy-CSF Is the magnetic susceptibility difference between oxygenated red blood cells and cerebrospinal fluid; x-shaped articles _oxy Magnetic susceptibility of oxygen-containing red blood cells; hct is hematocrit; pv is a correction parameter for the partial volume effect of the acquired voxels.

In calculating the first oxygen uptake fraction, χ _vein Quantitatively magnetizing the venous blood vessel in the first quantitative magnetizing rate map; in calculating the second oxygen uptake fraction, χ _vein And quantifying the magnetic susceptibility of the venous blood vessels in the second quantitative magnetic susceptibility map.

S250, determining a second oxygen uptake fraction of the target blood vessel of the brain region in a breath-hold state according to the second susceptibility weighted imaging and the vascularity map.

Similarly, a second quantitative susceptibility map corresponding to the second susceptibility weighted imaging may be determined first, and then, for each voxel of the target vessel in the vessel distribution map, a second oxygen uptake score of each voxel in the target vessel may be calculated according to the quantitative susceptibility of each voxel in the second quantitative susceptibility map and a relationship between a pre-established quantitative susceptibility and an oxygen uptake score.

Specifically, the second quantitative susceptibility solution may be performed on the brain region of the target object in the breath-hold state, so as to obtain a second quantitative susceptibility map corresponding to the second susceptibility weighted imaging.

Wherein, the specific manner of determining the second quantitative susceptibility map corresponding to the second susceptibility weighted imaging may be the same as the manner of determining the first quantitative susceptibility map. The relationship between the quantitative susceptibility and the oxygen uptake fraction may be determined based on the foregoing formula, and will not be described in detail herein.

S260, determining an evaluation index of the vascular reactivity of the target blood vessel according to the first oxygen uptake fraction and the second oxygen uptake fraction of the target blood vessel, and evaluating the vascular reactivity of the target blood vessel based on the evaluation index.

An exemplary embodiment of the present invention provides an experimental method of a vascular reactivity determination method. The specific steps and results of the experiment are as follows:

1. magnetic resonance imaging acquisition

(1) Head magnetic resonance data of a target subject is acquired. The whole body of the target object is required to be free from carrying metal and claustrophobia;

(2) And (3) data acquisition: the Siemens 3.0T magnetic resonance imaging system and the 32-channel phased array head coil are adopted to acquire three-time susceptibility weighted imaging SWI data of two healthy target objects, wherein the three-time susceptibility weighted imaging SWI data are respectively as follows: third susceptibility weighted imaging SWI of target object in free breathing state ₃ First susceptibility weighted imaging SWI of target object in free breathing state ₁ Second susceptibility weighted imaging SWI of target subject in breath-hold state ₂ And repeating the experiment once.

Fig. 3 is a schematic diagram of an experimental process of a method for evaluating vascular reactivity according to a second embodiment of the present invention.

Wherein the target object is subjected to the third magnetic susceptibility weighted imaging SWI in the free breathing state ₃ Is TR/TE ₁ Specifically 60/6.8ms, Δte=6.8 ms,7 echoes, FA of 15 °, matrix=320×240, each voxel size of 0.75mm×0.75mm×2mm, acquisition time of 4min; first susceptibility weighted imaging SWI of target object in free breathing state ₁ And the main imaging parameter is TR/TE, specifically 18/12ms, and FA is 15 degrees; second susceptibility weighted imaging SWI of target subject in breath-hold state ₂ The main imaging parameters of (a) are the same as those of the first susceptibility weighted imaging, and are also TR/TE, specifically 18/12ms, FA is 15 DEG, matrix=192×144, and voxel size is 1.2mm×1.2mm×5mm. The acquisition time of the first magnetic susceptibility weighted imaging is the same as that of the second magnetic susceptibility weighted imaging, and the acquisition time is 18s.

Where TR denotes a repetition time, i.e., a time required for the pulse sequence to be executed once; TE represents the echo time, i.e. the time required for the first rf pulse to generate an echo signal; FA represents a flip angle; matrix represents the size of a matrix, which may represent the number of pixels per voxel in susceptibility weighted imaging.

2. Data processing

Reconstructing a quantitative susceptibility map (Quantitative Susceptibility mapping, QSM) by using a bayesian regularization algorithm based on a phase diagram of Susceptibility Weighted Imaging (SWI) data, and extracting a venous vascular network of a brain region of a target object based on a priori template and Susceptibility Weighted Imaging (SWI) and Quantitative Susceptibility Map (QSM) of individual data. The change in vascular reactivity (OEF) is calculated using the mathematical relationship between the quantitative susceptibility asterisks of the quantitative susceptibility profile QSM and the vascular reactivity (OEF).

Wherein the OEF calculation formula is as follows:

Fig. 4 is a graph showing the results of the blood vessel reactivity oxygen uptake score in the method for evaluating blood vessel reactivity according to the second embodiment of the present invention. Results the paired T test statistical method is used to evaluate differences in vascular reactivity (OEF) between Free and Breath Hold (BH) groups. The p between the two OEF groups is less than 0.05, and the vascular reactivity OEF under breath-hold is improved by 8.9 percent compared with the resting OEF on average.

The above experiments demonstrate the feasibility of measurement of the vascular reactive oxygen uptake fraction.

It will be appreciated that the terms "first", "second" or "third" in embodiments of the invention are merely used to distinguish between different susceptibility weighted imaging or oxygen uptake scores, and are not limited in terms of order or magnitude of susceptibility weighted imaging or oxygen uptake scores, etc.

Example III

Fig. 5 is a schematic structural diagram of a blood vessel reactivity evaluation device according to a third embodiment of the present invention, where the blood vessel reactivity evaluation device according to the present embodiment may be implemented by software and/or hardware, and may be configured in a terminal and/or a server to implement a blood vessel reactivity evaluation method according to the embodiment of the present invention. The device specifically can include: a susceptibility weighted imaging acquisition module 510, a vascularity profile determination module 520, a first oxygen uptake score determination module 530, a vascular reactivity evaluation module 540, and a vascular reactivity evaluation module 550.

The magnetic susceptibility weighted imaging obtaining module 510 is configured to obtain a first magnetic susceptibility weighted imaging of a brain region of a target object in a free breathing state and a second magnetic susceptibility weighted imaging of the target object in a breath-hold state;

a vascularity map determination module 520 for determining a vascularity map of the brain region;

a first oxygen uptake fraction determination module 530 for determining a first oxygen uptake fraction of a target vessel of the brain region in a free breathing state from the first susceptibility weighted imaging and the vascularity map;

A second oxygen uptake score determination module 540 for determining a second oxygen uptake score of a target vessel of the brain region in a breath hold state from the second susceptibility weighted imaging and vascularity map;

a blood vessel reactivity evaluation module 550, configured to determine an evaluation index of the blood vessel reactivity of a target blood vessel according to the first oxygen uptake score and the second oxygen uptake score of the target blood vessel, and evaluate the blood vessel reactivity of the target blood vessel based on the evaluation index.

On the basis of any optional technical scheme in the embodiment of the invention, optionally, the vascularity map determining module specifically includes:

a third susceptibility weighted imaging acquisition sub-module for acquiring a third susceptibility weighted imaging of the brain region of the target object in a free breathing state, wherein an acquisition time of the third susceptibility weighted imaging is longer than an acquisition time of the first susceptibility weighted imaging;

the third quantitative magnetic susceptibility map determining submodule is used for determining a third quantitative magnetic susceptibility map corresponding to the third magnetic susceptibility weighted imaging;

and the vascularity map determining submodule is used for determining the vascularity map of the brain region according to the prior knowledge template of the brain region, the third magnetic susceptibility weighted imaging and the third quantitative magnetic susceptibility map.

Optionally, on the basis of any optional technical solution of the embodiment of the present invention, the first oxygen uptake fraction determining module specifically includes: a quantitative susceptibility map determination sub-module, a vascularity map determination sub-module, and an oxygen uptake fraction calculation sub-module.

The first quantitative magnetic susceptibility map determining submodule is used for determining a first quantitative magnetic susceptibility map corresponding to the first magnetic susceptibility weighted imaging;

The oxygen uptake score calculation sub-module is used for calculating a first oxygen uptake score of each voxel in the target blood vessel according to the quantitative magnetic susceptibility of each voxel in the second quantitative magnetic susceptibility map and a pre-established relationship between the quantitative magnetic susceptibility and the oxygen uptake score aiming at each voxel of the target blood vessel in the blood vessel distribution map.

On the basis of any optional technical scheme of the embodiment of the invention, optionally, the third quantitative susceptibility map determining submodule specifically includes: the device comprises a mask image generating unit, a susceptibility weighted imaging determining unit, a target phase image acquiring unit and a quantitative susceptibility map reconstructing unit.

The mask image generating unit is used for generating a brain mask image based on the original amplitude image of the third susceptibility weighted imaging;

a susceptibility weighted imaging determination unit configured to determine an intra-brain susceptibility weighted imaging corresponding to an intra-brain region in the brain region of the third susceptibility weighted imaging;

the target phase image acquisition unit is used for carrying out phase resolving processing and background field removing processing on the original phase image of the weighted imaging of the brain magnetic susceptibility to obtain a target phase image;

And the quantitative magnetic susceptibility map reconstruction unit is used for calculating the magnetic susceptibility distribution of each voxel of the brain internal region according to the amplitude priori information of the brain mask image, the target phase image and the least square method, and reconstructing a first quantitative magnetic susceptibility map.

On the basis of any optional technical scheme of the embodiment of the invention, optionally, the quantitative susceptibility map reconstruction unit is configured to perform regional phase winding estimation according to phase information and scanning time of a plurality of voxels of the original phase image of the weighted imaging of the susceptibility in the brain, and perform inverse solution on the aliasing phase based on the estimation result to obtain real phase information of the weighted imaging of the susceptibility in the brain.

On the basis of any optional technical scheme of the embodiment of the invention, optionally, the quantitative susceptibility map reconstruction unit is configured to remove a background field of the original phase image of the weighted imaging of the susceptibility in the brain based on a characteristic that an orthogonal product of a dipole field of a unit of a brain internal area of the brain area and a dipole field of a unit of any background field is smaller than a preset threshold.

On the basis of any optional technical scheme of the embodiment of the invention, optionally, the relation between the quantitative magnetic susceptibility and the oxygen uptake fraction is determined based on the following formula:

On the basis of any optional technical scheme in the embodiment of the invention, optionally, the vascular reactivity evaluation module is used for:

for each voxel of a target blood vessel, calculating a score difference value of the first oxygen uptake score and the second oxygen uptake score, and determining an evaluation index of the blood vessel reactivity of the target blood vessel according to the score difference value.

On the basis of any optional technical scheme in the embodiment of the invention, optionally, the acquisition time of the third susceptibility weighted imaging is longer than the acquisition time of the first susceptibility weighted imaging, the time difference between the acquisition time of the first susceptibility weighted imaging and the acquisition time of the second susceptibility weighted imaging is within a preset difference range, and the parameters of the scanning sequences adopted by the first susceptibility weighted imaging and the second susceptibility weighted imaging are the same.

The above-mentioned evaluation device for vascular reactivity can execute the evaluation method for vascular reactivity provided by any embodiment of the present invention, and has functional modules and beneficial effects corresponding to the execution of the evaluation method for vascular reactivity.

Example IV

Fig. 6 is a schematic structural diagram of an electronic device according to a fourth embodiment of the present invention. Fig. 6 illustrates a block diagram of an exemplary electronic device 12 suitable for use in implementing embodiments of the present invention. The electronic device 12 shown in fig. 6 is merely an example and should not be construed as limiting the functionality and scope of use of embodiments of the present invention.

As shown in fig. 6, the electronic device 12 is in the form of a general purpose computing device. Components of the electronic device 12 may include, but are not limited to: one or more processors or processing units 16, a system memory 28, a bus 18 that connects the various system components, including the system memory 28 and the processing units 16.

Bus 18 represents one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processor, and a local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA) bus, micro channel architecture (MAC) bus, enhanced ISA bus, video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnect (PCI) bus.

Electronic device 12 typically includes a variety of computer system readable media. Such media can be any available media that is accessible by electronic device 12 and includes both volatile and nonvolatile media, removable and non-removable media.

The system memory 28 may include computer system readable media in the form of volatile memory, such as Random Access Memory (RAM) 30 and/or cache memory 32. The electronic device 12 may further include other removable/non-removable, volatile/nonvolatile computer system storage media. By way of example only, storage system 34 may be used to read from or write to non-removable, nonvolatile magnetic media (not shown in FIG. 6, commonly referred to as a "hard disk drive"). Although not shown in fig. 6, a magnetic disk drive for reading from and writing to a removable non-volatile magnetic disk (e.g., a "floppy disk"), and an optical disk drive for reading from or writing to a removable non-volatile optical disk (e.g., a CD-ROM, DVD-ROM, or other optical media) may be provided. In such cases, each drive may be coupled to bus 18 through one or more data medium interfaces. The system memory 28 may include at least one program product having a set (e.g., at least one) of program modules configured to carry out the functions of the embodiments of the invention.

A program/utility 40 having a set (at least one) of program modules 42 may be stored in, for example, system memory 28, such program modules 42 including, but not limited to, an operating system, one or more application programs, other program modules, and program data, each or some combination of which may include an implementation of a network environment. Program modules 42 generally perform the functions and/or methods of the embodiments described herein.

The electronic device 12 may also communicate with one or more external devices 14 (e.g., keyboard, pointing device, display 24, etc.), one or more devices that enable a user to interact with the electronic device 12, and/or any devices (e.g., network card, modem, etc.) that enable the electronic device 12 to communicate with one or more other computing devices. Such communication may occur through an input/output (I/O) interface 22. Also, the electronic device 12 may communicate with one or more networks such as a Local Area Network (LAN), a Wide Area Network (WAN) and/or a public network, such as the Internet, through a network adapter 20. As shown in fig. 6, the network adapter 20 communicates with other modules of the electronic device 12 over the bus 18. It should be appreciated that although not shown in fig. 6, other hardware and/or software modules may be used in connection with electronic device 12, including, but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, data backup storage systems, and the like.

The processing unit 16 executes various functional applications and data processing by running a program stored in the system memory 28, for example, implementing a vascular reactivity evaluation method provided by the present embodiment.

Example five

A fifth embodiment of the present invention also provides a storage medium containing computer-executable instructions, which when executed by a computer processor, are for performing a method of evaluating vascular reactivity, the method comprising: acquiring a first magnetic susceptibility weighted imaging of a brain region of a target object in a free breathing state and a second magnetic susceptibility weighted imaging of the target object in a breath-hold state; determining a vascularity map of the brain region; determining a first oxygen uptake fraction of a target vessel of the brain region in a free breathing state from the first susceptibility weighted imaging and the vascularity map; determining a second oxygen uptake fraction of a target vessel of the brain region in a breath-hold state from the second susceptibility weighted imaging and a vascularity profile; determining an evaluation index of the vascular reactivity of a target blood vessel based on the first oxygen uptake score and the second oxygen uptake score of the target blood vessel, and evaluating the vascular reactivity of the target blood vessel based on the evaluation index.

The computer storage media of embodiments of the invention may take the form of any combination of one or more computer-readable media. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

The computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, either in baseband or as part of a carrier wave. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination of the foregoing. A computer readable signal medium may also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Computer program code for carrying out operations for embodiments of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, smalltalk, C ++ and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computer (for example, through the Internet using an Internet service provider).

Note that the above is only a preferred embodiment of the present invention and the technical principle applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, while the invention has been described in connection with the above embodiments, the invention is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the invention, which is set forth in the following claims.

Claims

1. A method for evaluating vascular reactivity, comprising:

determining a vascularity map of the brain region;

2. The method of claim 1, wherein said determining a vascularity map of the brain region comprises:

acquiring third susceptibility weighted imaging of a brain region of a target object in a free breathing state, wherein the acquisition time of the third susceptibility weighted imaging is longer than that of the first susceptibility weighted imaging;

determining a third quantitative susceptibility map corresponding to the third susceptibility weighted imaging;

determining a vascularity map of the brain region from the prior knowledge template of the brain region, the third susceptibility weighted imaging, and the third quantitative susceptibility map.

3. The method of claim 1, wherein said determining a first oxygen uptake fraction of the brain region in a free breathing state from the first susceptibility weighted imaging and vascularity map comprises:

determining a first quantitative susceptibility map corresponding to the first susceptibility weighted imaging;

And calculating a first oxygen uptake score of each voxel in the target blood vessel according to the quantitative magnetic susceptibility of each voxel in the first quantitative magnetic susceptibility map and a pre-established relationship between the quantitative magnetic susceptibility and the oxygen uptake score aiming at each voxel of the target blood vessel in the blood vessel distribution map.

4. The method of claim 2, wherein the determining a third quantitative susceptibility map for the third susceptibility weighted imaging comprises:

generating a brain mask image based on the raw amplitude image of the third susceptibility weighted imaging;

determining an intra-brain susceptibility weighted imaging of the brain region of the third susceptibility weighted imaging corresponding to an intra-brain region;

performing phase resolution processing and background field removal processing on the original phase image of the weighted imaging of the brain magnetic susceptibility to obtain a target phase image;

and calculating the magnetic susceptibility distribution of each voxel in the brain internal region according to the amplitude priori information of the brain mask image, the target phase image and the least square method, and reconstructing a third quantitative magnetic susceptibility map.

5. The method of claim 4, wherein the dephasing the raw phase image of the intra-brain susceptibility weighted imaging comprises:

And carrying out regional phase winding estimation according to the phase information and the scanning time of a plurality of voxels of the original phase image of the weighted imaging of the cerebral magnetic susceptibility, and carrying out inverse solution on the aliasing phase based on the estimation result to obtain the real phase information of the weighted imaging of the cerebral magnetic susceptibility.

6. The method of claim 5, wherein the dephasing and background field removal of the raw phase image of the weighted imaging of brain susceptibility comprises:

and removing the background field of the original phase image of the weighted imaging of the cerebral magnetic susceptibility based on the characteristic that the orthogonal product of the unit dipole field of the cerebral internal area of the cerebral area and the unit dipole field of any background field is smaller than a preset threshold.

7. A method according to claim 3, wherein the relationship between the quantitative susceptibility and oxygen uptake fraction is determined based on the following formula:

wherein OEF is the oxygen uptake fraction of the voxel; Δχ _vein-CSF ＝χ _vein -χ _CSF ，χ _vein Quantitative susceptibility, χ, of venous vessels in the quantitative susceptibility profile _CSF Quantitative susceptibility to cerebrospinal fluid in the anterior lateral ventricle region; Δχ _vein-CSF Indicating venous vessel and cerebrospinal fluid susceptibility differences; Δχ _deoxy Differential magnetic susceptibility of oxygenated and deoxygenated erythrocytes per unit of hematocrit Different; Δχ _oxy-CSF ＝χ _oxy -χ _CSF ，Δχ _oxy-CSF Is the magnetic susceptibility difference between oxygenated red blood cells and cerebrospinal fluid; x-shaped articles _oxy Magnetic susceptibility of oxygen-containing red blood cells; hct is hematocrit; pv is a correction parameter for the partial volume effect of the acquired voxels.

8. The method of claim 1, wherein the determining an evaluation index of vascular reactivity of the target blood vessel from the first oxygen uptake score and the second oxygen uptake score of the target blood vessel comprises:

9. The method of claim 1, wherein a time difference between the acquisition time of the first susceptibility weighted imaging and the acquisition time of the second susceptibility weighted imaging is within a preset difference range, and wherein parameters of a scan sequence employed by the first susceptibility weighted imaging and the second susceptibility weighted imaging are the same.

10. An apparatus for evaluating vascular reactivity, comprising: