Dual-mode acoustic imaging method and system

Abstract

The invention provides a dual-mode acoustic imaging method which comprises the following steps: continuously acquiring multiple frames of ultrasonic images of a target area, and filtering the multiple frames of ultrasonic images to extract microbubble images in the multiple frames of ultrasonic images; performing tracking processing on each microbubble image to obtain a blood flow super-resolution image of the target area; emitting light beams with different wavelengths to a target area to obtain a plurality of photoacoustic images under different wavelengths; processing the plurality of photoacoustic images based on the spectral absorption characteristics of different substances in the target area to obtain blood oxygen saturation information of the target area; based on the blood flow super-resolution image and the oxyhemoglobin saturation information, a fused image of the target area is obtained. According to the invention, ultrasonic imaging and optical imaging are combined, so that the system has the advantages of high spatial resolution of optical imaging and strong penetrating power of ultrasonic imaging; the imaging method has cerebrovascular multi-dimensional information including tissue structure, blood flow and blood oxygen saturation information, so that the imaging method meets the requirements of cerebral blood flow detection in time and space.

Description

Technical Field

[0001] The present invention belongs to the technical field of transducers, and in particular relates to a dual-mode acoustic imaging method and system. Background Art

[0002] The study of brain activity and brain function characteristics is a core component of brain science research. At present, the exact mechanism of functional brain diseases is still unclear, and there is a lack of effective treatment measures. This remains a scientific and medical challenge faced by the world. Therefore, understanding the spatiotemporal characteristics of brain activity related to the pathology of these functional brain diseases and developing advanced intervention and treatment technologies are major and urgent tasks for the scientific community. Brain activity is different from any other organ in the body in terms of time. The brain receives and processes sensory perceptions, and its organ and internal sources are complex neural signals with high time dependence. This determines the high variability of brain activity in the time dimension, which poses great challenges to the tools, methods and theoretical frameworks of brain science research.

[0003] Among the existing brain imaging, only magnetic resonance BOLD imaging technology is available. However, due to the limitations of magnetic resonance equipment, it is expensive and has limited spatiotemporal resolution, which limits its application in some brain sciences. Contrast-enhanced ultrasound (CEUS), as a popular clinical tool, can be used to characterize tissue microvessels due to its affordable price, wide accessibility, and the characteristics of non-ionizing radiation ultrasound. However, the resolution of this type of ultrasound imaging is limited, making it challenging to use ultrasound angiography to display microvessels. In addition, the data obtained by magnetic resonance BOLD imaging or other imaging technologies are single, making it difficult to accurately analyze brain functional activities in spatial and temporal dimensions based on tissue structure, and cannot meet the needs of cerebral blood flow detection in terms of temporal and spatial resolution. Summary of the invention

[0004] In order to overcome the defects of the above-mentioned prior art, the present application proposes a dual-mode acoustic imaging method and system for the brain, which combines ultrasonic imaging and optical imaging so that it has the advantages of high spatial resolution of optical imaging and strong penetration of ultrasonic imaging; and the imaging method has multi-dimensional information of cerebral blood vessels including tissue structure, blood flow and blood oxygen saturation information, so that it can meet the needs of cerebral blood flow detection in time and space.

[0005] This is achieved specifically through the following technical solutions:

[0006] A dual-mode acoustic imaging method, comprising:

[0007] Continuously acquiring multiple frames of ultrasound images of the target area, filtering the multiple frames of ultrasound images to extract microbubble images in the multiple frames of ultrasound images; tracking each of the microbubble images in the multiple frames of ultrasound images to obtain a blood flow super-resolution image of the target area;

[0008] Emitting light beams of different wavelengths to a target area to obtain a plurality of photoacoustic images at different wavelengths; processing the plurality of photoacoustic images based on spectral absorption characteristics of different substances in the target area to obtain blood oxygen saturation information of the target area;

[0009] Based on the blood flow super-resolution image and the blood oxygen saturation information, blood oxygen metabolism information of the target area is generated; based on the blood oxygen metabolism information and the blood flow super-resolution image, feature fusion is performed to obtain a fused image of the target area.

[0010] In a specific embodiment, each frame of the ultrasound image is acquired by the following steps:

[0011] Transmitting an ultrasonic beam to cover the target area based on an ultrasonic probe, so that the target area returns an ultrasonic echo signal;

[0012] Delaying the ultrasonic echo signal received by each array element in the ultrasonic probe based on the relative position between the array element of the ultrasonic probe and the target area;

[0013] The delayed ultrasonic echo signals are superimposed to obtain the ultrasonic image of the target area.

[0014] In a specific embodiment, each frame of the ultrasound image is acquired by the following steps:

[0015] Delay control of the ultrasonic beam of the ultrasonic probe so that the ultrasonic beam of the ultrasonic probe is deflected at a preset deflection angle and scans the target area back and forth; based on the ultrasonic beam of the ultrasonic probe under multiple deflections, a plurality of images to be processed at different deflection angles are obtained;

[0016] The multiple images to be processed at different deflection angles are superimposed to obtain the ultrasonic image of the target area.

[0017] In a specific embodiment, the “filtering the multiple frames of ultrasound images to extract microbubble images in the multiple frames of ultrasound images; tracking each of the microbubble images in the multiple frames of ultrasound images to obtain a blood flow super-resolution image of the target area” includes:

[0018] Filtering the multiple frames of ultrasound images through a filter to extract multiple microbubble images from the multiple frames of ultrasound images, each frame of the ultrasound image having at least two microbubble images;

[0019] Positioning all the microbubble images in each of the ultrasound images to obtain position information of each of the microbubble images;

[0020] Pairing the microbubble images in two adjacent frames of ultrasound images based on the position information of the microbubble images and the microbubble pairing principle of two adjacent frames of ultrasound images;

[0021] When a certain microbubble image is paired in multiple consecutive frames of ultrasound images, a microbubble motion trajectory is generated based on the microbubble image;

[0022] When a preset number of microbubble motion trajectories are acquired, the blood flow super-resolution image is generated based on the preset number of microbubble motion trajectories.

[0023] In a specific embodiment, the “locating all the microbubble images in each of the ultrasound images to obtain position information of each of the microbubble images” includes:

[0024] acquiring a point spread function of the microbubble image in the ultrasound image,

[0025] Acquire the coordinates of each point of the microbubble image, and determine the point spread function value corresponding to each point coordinate of the microbubble image based on the coordinates of each point of the microbubble image and the point spread function;

[0026] Positioning the microbubble image based on the maximum value of the point spread function values ​​corresponding to the coordinates of each point of the microbubble image to determine the target point coordinates of the microbubble image, and using the target point coordinates of the microbubble image as the position information of the microbubble image;

[0027] The point coordinates of the microbubble image are expressed as (x, y, z), and the point spread function is expressed as σ x is the half maximum width of the point spread function along the x-axis, σ y is the half-maximum full width of the point spread function along the y-axis, σ z is the full width at half maximum of the point spread function along the z-axis,

[0028] In a specific embodiment, the microbubble pairing principle of two adjacent frames of ultrasound images includes: the sum of distances between multiple groups of paired microbubble images of two adjacent frames of ultrasound images is the smallest;

[0029] The “pairing each of the microbubble images in two adjacent frames of ultrasound images based on the position information of the microbubble images and the microbubble pairing principle of the two adjacent frames of ultrasound images” includes:

[0030] Based on the position information of each of the microbubble images in two adjacent frames of the ultrasound image, each of the microbubble images in two adjacent frames of the ultrasound image is paired so that the sum of the distances between multiple groups of paired microbubble images is minimized.

[0031] In a specific embodiment, the step of “emitting light beams of different wavelengths to the target area” includes: selecting a plurality of light beams of different wavelengths based on a preset wavelength range, wherein the preset wavelength range is between 700 nm and 900 nm;

[0032] The “emitting light beams of different wavelengths to the target area to obtain a plurality of photoacoustic images at different wavelengths” includes: sequentially emitting light beams of different wavelengths to cover the target area based on an optical signal emitting device, so that the target area sequentially returns different ultrasonic echo signals; and acquiring a plurality of photoacoustic images at different wavelengths based on the plurality of different ultrasonic echo signals and through an image reconstruction algorithm;

[0033] The “processing the plurality of photoacoustic images based on the spectral absorption characteristics of different substances in the target area to obtain the blood oxygen saturation information of the target area” includes:

[0034] Based on the spectral absorption characteristics of the first chromophore substance and the second chromophore substance in the target area, processing the plurality of photoacoustic images to extract the photoacoustic component corresponding to each of the photoacoustic images;

[0035] The blood oxygen saturation information of the target area is generated based on the photoacoustic component corresponding to each of the photoacoustic images, the wavelength of each of the light beams, the absorption coefficient of the first chromophore substance in the target area, the absorption coefficient of the second chromophore substance in the target area, and the absorption coefficient of the third chromophore substance in the target area; wherein the first chromophore substance includes oxygenated hemoglobin, the second chromophore substance includes deoxygenated hemoglobin, and the third chromophore substance includes other chromophore substances except oxygenated hemoglobin and deoxygenated hemoglobin.

[0036] In a specific embodiment, it also includes:

[0037] The light beam emitted by the optical signal emitting device is divided into a first light beam and a second light beam by a light beam splitter, and the energy value of the first light beam is equal to the energy value of the second light beam; the first light beam is configured to cover the target area so that the target area returns a photoacoustic echo signal; the second light beam is configured to monitor the energy value of the second light beam by an energy monitoring device, so as to monitor the energy value of the first light beam in real time based on the energy value of the second light beam.

[0038] A dual-mode acoustic imaging system, comprising:

[0039] An ultrasonic imaging module, used for continuously acquiring multiple frames of ultrasonic images of a target area, filtering the multiple frames of ultrasonic images to extract microbubble images in the multiple frames of ultrasonic images; tracking and processing each of the microbubble images in the multiple frames of ultrasonic images to obtain a blood flow super-resolution image of the target area;

[0040] An optical imaging module, used for emitting light beams of different wavelengths to a target area to obtain a plurality of photoacoustic images at different wavelengths; processing the plurality of photoacoustic images based on the spectral absorption characteristics of different substances in the target area to obtain blood oxygen saturation information of the target area;

[0041] The image fusion module is used to generate blood oxygen metabolism information of the target area based on the blood flow super-resolution image and the blood oxygen saturation information; and perform feature fusion based on the blood oxygen metabolism information and the blood flow super-resolution image to obtain a fused image of the target area.

[0042] In a specific embodiment, the ultrasound imaging module includes:

[0043] A first processing module is used to transmit an ultrasonic beam to cover the target area based on an ultrasonic probe, so that the target area returns an ultrasonic echo signal; based on the relative position between the array element of the ultrasonic probe and the target area, delay the ultrasonic echo signal received by each array element in the ultrasonic probe;

[0044] A first superposition module, used for superimposing each of the delayed ultrasonic echo signals to obtain the ultrasonic image of the target area;

[0045] And / or, the ultrasound imaging module comprises:

[0046] A second processing module is used for delaying the control of the ultrasonic beam of the ultrasonic probe so that the ultrasonic beam of the ultrasonic probe is deflected at a preset deflection angle and scans the target area back and forth; based on the ultrasonic beam of the ultrasonic probe under multiple deflections, a plurality of images to be processed under different deflection angles are obtained;

[0047] The second superposition module is used to superimpose a plurality of the images to be processed at different deflection angles to obtain the ultrasonic image of the target area.

[0048] This application has at least the following beneficial effects:

[0049] The present application proposes a dual-mode acoustic imaging method, comprising: continuously acquiring multiple frames of ultrasound images of a target area, filtering the multiple frames of ultrasound images to extract microbubble images in the multiple frames of ultrasound images; tracking and processing each microbubble image in the multiple frames of ultrasound images to obtain a blood flow super-resolution image of the target area; emitting light beams of different wavelengths to the target area to obtain multiple photoacoustic images at different wavelengths; processing the multiple photoacoustic images based on the spectral absorption characteristics of different substances in the target area to obtain blood oxygen saturation information of the target area; generating blood oxygen metabolism information of the target area based on the blood flow super-resolution image and the blood oxygen saturation information; and performing feature fusion based on the blood oxygen metabolism information and the blood flow super-resolution image to obtain a fused image of the target area. The present application processes multiple frames of ultrasound images to track each microbubble image, thereby obtaining a blood flow super-resolution image of a target area containing brain blood flow morphology, blood flow velocity, blood vessel diameter information, and blood vessel area, and simultaneously emits light beams of different wavelengths to the target area to obtain blood oxygen saturation information through multi-wavelength optical imaging technology; and processes and fuses the blood oxygen saturation information and the blood flow super-resolution image to obtain a fused image of the target area. On the one hand, the fused image is a fused image obtained based on the combination of ultrasound imaging and optical imaging, and has the advantages of high spatial resolution of optical imaging and strong penetration of ultrasound imaging; on the other hand, the fused image not only has the cerebral vascular tissue structure and blood flow flow information obtained by ultrasound imaging, but also has the blood oxygen saturation information obtained by optical imaging. The fused image provides multi-dimensional information of the cerebral blood vessels, so that it meets the needs of cerebral blood flow detection in terms of time and spatial resolution, and provides important data for characterizing brain nerve / functional activities.

[0050] Furthermore, each frame of ultrasound image is acquired through the following steps: based on the ultrasound probe, an ultrasound beam is emitted to cover the target area so that the target area returns an ultrasound echo signal; based on the relative position between the array elements of the ultrasound probe and the target area, the ultrasound echo signals received by each array element in the ultrasound probe are delayed; and each delayed ultrasound echo signal is superimposed to obtain an ultrasound image of the target area. The present application can achieve complete imaging of the target area with only one emission through the above-mentioned imaging method, thereby greatly improving the frame rate of ultrasound imaging, so as to facilitate real-time and accurate observation of the dynamic changes of the target area based on the ultrasound image.

[0051] Furthermore, each frame of ultrasound image is acquired through the following steps: delay control of the ultrasound beam of the ultrasound probe so that the ultrasound beam of the ultrasound probe is deflected at a preset deflection angle and scans the target area back and forth; based on the ultrasound beam of the ultrasound probe under multiple deflections, multiple images to be processed at different deflection angles are acquired; multiple images to be processed at different deflection angles are superimposed to obtain an ultrasound image of the target area. The present application deflects the transmitted sound beam at multiple angles through delay control to obtain multiple images, and superimposes the multiple images to achieve an effect similar to coherent focusing, thereby ensuring that the imaging frame rate reaches more than one thousand frames while greatly improving the imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0053] Figure 1 Schematic diagram of the dual-mode acoustic imaging method of Example 1 of the present application Figure 1 ;

[0054] Figure 2 Schematic diagram of the dual-mode acoustic imaging method of Example 1 of the present application Figure 2 ;

[0055] Figure 3 Schematic diagram of the dual-mode acoustic imaging method of Example 1 of the present application Figure 3 ;

[0056] Figure 4 Schematic diagram of the dual-mode acoustic imaging method of Example 1 of the present application Figure 4 ;

[0057] Figure 5 Schematic diagram of the dual-mode acoustic imaging method of Example 1 of the present application Figure 5 ;

[0058] Figure 6 This is a module schematic diagram of the dual-mode acoustic imaging system of Example 2 of the present application.

[0059] Reference numerals:

[0060] 1-ultrasound imaging module; 2-photoacoustic imaging module; 3-image fusion module;

[0061] 11-first processing module; 12-first superposition module; 13-second processing module; 14-second superposition module;

[0062] 21-photoacoustic image acquisition module; 22-photoacoustic component extraction module; 23-blood oxygen saturation acquisition module. DETAILED DESCRIPTION

[0063] Hereinafter, various embodiments of the present application will be described more fully. The present application may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of the present application to the specific embodiments disclosed herein, but the present application should be understood to cover all adjustments, equivalents and / or alternatives within the spirit and scope of the various embodiments of the present application.

[0064] Hereinafter, the term "include" or "may include" used in various embodiments of the present application indicates the presence of a disclosed function, operation, or element, and does not limit the addition of one or more functions, operations, or elements. In addition, as used in various embodiments of the present application, the terms "include", "have", and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components, or a combination of the foregoing or the possibility of adding one or more features, numbers, steps, operations, elements, components, or a combination of the foregoing.

[0065] Example 1

[0066] like Figure 1 As shown, the present application proposes a dual-mode acoustic imaging method, comprising:

[0067] S1: continuously acquiring multiple frames of ultrasound images of the target area, filtering the multiple frames of ultrasound images to extract microbubble images in the multiple frames of ultrasound images; tracking each microbubble image in the multiple frames of ultrasound images to obtain a blood flow super-resolution image of the target area;

[0068] S2: emitting light beams of different wavelengths to the target area to obtain a plurality of photoacoustic images at different wavelengths; processing the plurality of photoacoustic images based on the spectral absorption characteristics of different substances in the target area to obtain blood oxygen saturation information of the target area;

[0069] S3: Generate blood oxygen metabolism information of the target area based on the blood flow super-resolution image and the blood oxygen saturation information; perform feature fusion based on the blood oxygen metabolism information and the blood flow super-resolution image to obtain a fused image of the target area.

[0070] The present application processes multiple frames of ultrasound images to track each microbubble image, thereby obtaining a blood flow super-resolution image of a target area containing brain blood flow morphology, blood flow velocity, blood vessel diameter information, and blood vessel area, and simultaneously emits light beams of different wavelengths to the target area to obtain blood oxygen saturation information through multi-wavelength optical imaging technology; and processes and fuses the blood oxygen saturation information and the blood flow super-resolution image to obtain a fused image of the target area. On the one hand, the fused image is a fused image obtained based on the combination of ultrasound imaging and optical imaging, and has the advantages of high spatial resolution of optical imaging and strong penetration of ultrasound imaging; on the other hand, the fused image not only has the cerebral vascular tissue structure and blood flow flow information obtained by ultrasound imaging, but also has the blood oxygen saturation information obtained by optical imaging. The fused image provides multi-dimensional information of the cerebral blood vessels, so that it meets the needs of cerebral blood flow detection in terms of time and spatial resolution, and provides important data for characterizing brain nerve / functional activities.

[0071] Among them, Figure 2 As shown, in step S1, each frame of ultrasound image is acquired through the following steps: based on the ultrasound probe, an ultrasound beam is emitted to cover the target area so that the target area returns an ultrasound echo signal; based on the relative position between the array elements of the ultrasound probe and the target area, the ultrasound echo signals received by each array element in the ultrasound probe are delayed; each delayed ultrasound echo signal is superimposed to obtain an ultrasound image of the target area. The present application can achieve complete imaging of the target area with only one emission through the above imaging method, thereby greatly improving the frame rate of ultrasound imaging, so as to facilitate real-time and accurate observation of dynamic changes of the target area based on the ultrasound image.

[0072] like Figure 3 As shown, in step S1, each frame of ultrasound image can also be acquired through the following steps: delay control of the ultrasound beam of the ultrasound probe so that the ultrasound beam of the ultrasound probe is deflected at a preset deflection angle and scans the target area back and forth; based on the ultrasound beam of the ultrasound probe under multiple deflections, a plurality of images to be processed at different deflection angles are acquired; the plurality of images to be processed at different deflection angles are superimposed to obtain an ultrasound image of the target area. The present application deflects the transmitted sound beam at multiple angles through delay control to obtain multiple images, and superimposes the multiple images to achieve an effect similar to coherent focusing, thereby ensuring that the imaging frame rate reaches more than one thousand frames while greatly improving the imaging quality.

[0073] like Figure 4As shown, since the blood flow signal is weaker in amplitude than the tissue signal, it is masked by the tissue signal in the ultrasonic B-mode image, and it is difficult to observe the blood flow signal. Therefore, after collecting multiple frames of continuous cerebral blood flow ultrasound images through thousand-frame ultrasound imaging technology, the ultrasound image needs to be further processed to extract the microbubble image to achieve cerebral blood flow imaging. Compared with tissue signals, blood signals have weaker signal amplitudes, but change faster over time. Compared with randomly distributed noise signals, blood signals have stronger amplitudes, but their frequency of change over time is lower. Therefore, the present application uses a filter to filter continuous ultrasound images according to the differences between blood signals and tissues and noise signals in signal amplitude, time-space frequency and other dimensions to extract blood signals for the next step of processing, specifically:

[0074] In step S1, "filtering multiple frames of ultrasound images to extract microbubble images from the multiple frames of ultrasound images" includes: filtering the multiple frames of ultrasound images through a filter to extract multiple microbubble images from the multiple frames of ultrasound images, each frame of ultrasound image has at least two microbubble images.

[0075] In this embodiment, the multiple frames of ultrasound images are 100-200 frames of ultrasound images; the 100-200 frames of ultrasound images are filtered by a wall filter to extract multiple microbubble images in the 100-200 frames of ultrasound images, and each frame of ultrasound image has at least two microbubble images.

[0076] After acquiring the microbubble image, it is also necessary to locate the microbubble image. Since the microbubble acoustic reflection is strong and the particle size is much smaller than the imaging wavelength, it is often shown in the image as a strong amplitude and the image is close to the point spread function of the system. Based on the above characteristics of microbubble acoustic reflection, the microbubble image is located with sub-micron precision in the next step; after positioning, motion tracking is performed based on the position of each frame of the microbubble image to generate a blood flow super-resolution image, specifically:

[0077] “Tracking and processing each microbubble image in a multi-frame ultrasound image to obtain a blood flow super-resolution image of a target area” includes:

[0078] Positioning all microbubble images in each ultrasound image to obtain position information of each microbubble image;

[0079] Based on the position information of each microbubble image and the microbubble pairing principle of two adjacent frames of ultrasound images, each microbubble image in two adjacent frames of ultrasound images is paired;

[0080] When a certain microbubble image is paired in multiple consecutive frames of ultrasound images, a microbubble motion trajectory is generated based on the microbubble image;

[0081] When a preset number of microbubble motion trajectories are acquired, a blood flow super-resolution image is generated based on the preset number of microbubble motion trajectories.

[0082] The present application obtains microbubble images, and locates, pairs, and tracks the microbubble images to obtain blood flow super-resolution images to improve image clarity and data accuracy.

[0083] like Figure 5 As shown in the figure, due to the diffraction limit, when the distance between two points is less than half of the imaging wavelength, the diffraction images of the two points will interfere with each other, and the two points cannot be distinguished in the ultrasound image. However, the present application uses the diffraction images of two adjacent points to locate the points separately, and only retains the position of the target point, avoiding diffraction interference and realizing super-resolution imaging. Specifically:

[0084] “Locate all microbubble images in each ultrasound image to obtain position information of each microbubble image” includes:

[0085] Get the point spread function of the microbubble image in the ultrasound image,

[0086] Acquiring the coordinates of each point of the microbubble image, and determining the point spread function value corresponding to the coordinates of each point of the microbubble image based on the coordinates of each point of the microbubble image and the point spread function;

[0087] Based on the maximum value of the point spread function value corresponding to each point coordinate of the microbubble image, the microbubble image is positioned to determine the target point coordinate of the microbubble image, and the target point coordinate of the microbubble image is used as the position information of the microbubble image;

[0088] The point coordinates of the microbubble image are expressed as (x, y, z), and the point spread function is expressed as is the half-maximum full width of the point spread function along the x-axis, is the half-maximum full width of the point spread function along the y-axis, is the half-maximum full width of the point spread function along the z-axis,

[0089] The point spread function has the following characteristics: the signal amplitude at the center point is the highest, and the signal amplitudes of the surrounding points are symmetrical about the center. Therefore, based on this characteristic, the target point position of the microbubble image is determined by the maximum value of the point spread function value corresponding to the coordinates of each point in the microbubble image, or the microbubble image is located by finding the symmetric center of the signal amplitude.

[0090] After obtaining the position information of the microbubble image, in order to further realize flow velocity imaging, it is necessary to track the motion of the microbubble. The microbubble pairing principle of two adjacent frames of ultrasound images includes: the sum of the distances between multiple groups of paired microbubble images of two adjacent frames of ultrasound images is the smallest, specifically:

[0091] “Pairing each microbubble image in two adjacent frames of ultrasound images based on the position information of the microbubble images and the microbubble pairing principle of two adjacent frames of ultrasound images” includes: pairing each microbubble image in two adjacent frames of ultrasound images based on the position information of each microbubble image in two adjacent frames of ultrasound images so that the sum of the distances between multiple groups of paired microbubble images is minimized.

[0092] For example, there are M microbubbles m in the tth frame and N microbubbles n in the t+1th frame. That is, if there are L pairs, d(m l ,n l ) represents the distance between two paired microbubbles in two frames of images. The pairing principle is to minimize the sum of the total pairing distances between all microbubbles.

[0093] After achieving continuous multi-frame pairing through the above method, when a certain microbubble image is paired in multiple continuous frames of ultrasound images, a microbubble motion trajectory is generated based on the microbubble image; when a preset number of microbubble motion trajectories are obtained, a blood flow super-resolution image is generated based on the preset number of microbubble motion trajectories. Similarly, by continuously acquiring blood flow super-resolution images, the continuous changes in vascular structure and blood flow velocity can be obtained, thereby achieving continuous super-resolution ultrasound functional imaging. The present application uses a new three-dimensional super-resolution method to utilize the unique properties of ultrasonic microbubbles, combining wide-beam ultrasound with microbubbles, and breaking through the limitations of the diffraction limit of traditional imaging through algorithms to achieve three-dimensional ultrasonic high-resolution blood flow imaging of less than 30 microns.

[0094] In the detection of cerebral blood flow, blood oxygen saturation information is an important reference data. The basic principle of obtaining blood oxygen saturation information is photoacoustic oxygen metabolism imaging. Since each substance in the tissue corresponds to a specific light absorption characteristic, multi-wavelength laser can be used to irradiate the tissue, and the light absorption spectrum information of the tissue can be obtained through photoacoustic imaging, and then the solubility of the chemical components of the biological tissue can be quantitatively analyzed. Hemoglobin has two forms, oxygenated hemoglobin and deoxygenated hemoglobin, which have different absorption characteristics for electromagnetic waves of different wavelengths. Using a dual-wavelength photoacoustic imaging system to image living biological tissues, not only the total hemoglobin content in the area can be obtained, but also the relative content of oxygenated hemoglobin and deoxygenated hemoglobin can be obtained, and then the blood oxygen saturation information can be calculated, and then the arterial and venous systems can be distinguished from the photoacoustic image. Since hemoglobin is the most important oxygen carrier, it is closely related to the metabolic process of the organism. Photoacoustic imaging of hemoglobin can sensitively reflect the metabolism of the organism and the physiological function information related to it, which has important medical significance for the study of brain function imaging.

[0095] Based on the principle of photoacoustic imaging, different substances have different absorption of light, and thus show different photoacoustic signal intensities. The brain is rich in blood vessels, and hemoglobin has a strong absorption of light, which shows a strong photoacoustic signal. In addition, at different excitation wavelengths, oxyhemoglobin and deoxyhemoglobin have different photoacoustic spectral characteristics. Therefore, multispectral photoacoustic imaging can be used to perform highly specific and sensitive quantitative imaging of blood oxygen saturation. Specifically:

[0096] Before "emitting light beams of different wavelengths to the target area" in step S2, the method includes: selecting a plurality of light beams of different wavelengths based on a preset wavelength range, wherein the preset wavelength range is between 700 nm and 900 nm.

[0097] In this embodiment, 21 wavelengths, including 700 nm, 710 nm, 720 nm, ..., 900 nm, can be used to perform rapid photoacoustic imaging of the target area.

[0098] In step S2, "emitting light beams of different wavelengths to the target area to obtain multiple photoacoustic images at different wavelengths" includes: based on the optical signal emitting device, sequentially emitting light beams of different wavelengths to cover the target area, so that the target area returns different ultrasonic echo signals in turn; based on multiple different ultrasonic echo signals and through an image reconstruction algorithm, multiple photoacoustic images at different wavelengths are obtained.

[0099] “Processing multiple photoacoustic images based on the spectral absorption characteristics of different substances in the target area to obtain blood oxygen saturation information of the target area” includes:

[0100] Based on the spectral absorption characteristics of the first chromophore substance and the second chromophore substance in the target area, the plurality of photoacoustic images are processed to extract the photoacoustic component corresponding to each photoacoustic image;

[0101] The blood oxygen saturation information of the target area is generated based on the photoacoustic component corresponding to each photoacoustic image, the wavelength of each light beam, the absorption coefficient of the first chromophore substance in the target area, the absorption coefficient of the second chromophore substance in the target area, and the absorption coefficient of the third chromophore substance in the target area; wherein the first chromophore substance includes oxygenated hemoglobin, the second chromophore substance includes deoxygenated hemoglobin, and the third chromophore substance includes other chromophore substances except oxygenated hemoglobin and deoxygenated hemoglobin, such as cytochrome oxidase or melanin.

[0102] Among them, the expression of blood oxygen saturation information is μ1 is the absorption coefficient of the first chromophore substance in the target area, μ2 is the absorption coefficient of the second chromophore substance in the target area, μ3 is the absorption coefficient of the third chromophore substance in the target area, C nThe photoacoustic component corresponds to each photoacoustic image, and the photoacoustic component includes the intensity or frequency of the photoacoustic echo signal.

[0103] Furthermore, considering that the laser pulse energy has a certain volatility, the energy of each excitation light pulse needs to be monitored in the multi-wavelength photoacoustic imaging system to perform energy correction on the signal intensity of the light beam, thereby accurately quantifying the photoacoustic signal intensity generated by oxyhemoglobin and deoxyhemoglobin, and realizing accurate monitoring of blood oxygen saturation;

[0104] The dual-mode acoustic imaging method of the present application also includes: the light beam emitted by the optical signal emitting device is divided into a first light beam and a second light beam through a beam splitter, and the energy value of the first light beam and the energy value of the second light beam are equal; the first light beam is configured to cover the target area so that the target area returns a photoacoustic echo signal; the second light beam is configured to monitor the energy value of the second light beam through an energy monitoring device, so as to monitor the energy value of the first light beam in real time based on the energy value of the second light beam, and accurate monitoring of blood oxygen saturation is achieved by real-time monitoring of the energy value of the first light beam.

[0105] In step S3, “generating blood oxygen metabolism information of the target area based on the blood flow super-resolution image and the blood oxygen saturation information; performing feature fusion based on the blood oxygen metabolism information and the blood flow super-resolution image to obtain a fused image of the target area” includes:

[0106] Generate blood oxygen metabolism information of the target area based on blood flow information and blood oxygen saturation information in the blood flow super-resolution image;

[0107] Extracting first characteristic data such as blood oxygen content, blood oxygen partial pressure, blood oxygen capacity, and blood oxygen saturation information based on blood oxygen metabolism information; extracting second characteristic data such as vascular structure image and blood flow velocity based on blood flow super-resolution image;

[0108] The first feature data and the second feature data are superimposed and fused to obtain a fused image of the target area.

[0109] The fused image has the advantages of high spatial resolution of optical imaging and strong penetration of ultrasonic imaging; and the fused image has the cerebral vascular tissue structure and blood flow information obtained by ultrasonic imaging, and the blood oxygen saturation information obtained by optical imaging. The fused image provides multi-dimensional information of the cerebral blood vessels, so that it can meet the needs of cerebral blood flow detection in terms of time and spatial resolution. The establishment of appropriate physiological and mathematical models can present multi-dimensional information images of brain blood supply including vascular structure, blood flow, and oxygen metabolism at the whole brain level, realizing multi-modal information and image fusion display.

[0110] It can be seen that the dual-mode acoustic imaging method of the present application processes multiple frames of ultrasound images to track each microbubble image, obtains a blood flow super-resolution image of the target area containing brain blood flow morphology, blood flow velocity, vascular diameter information and vascular area, and at the same time, by emitting light beams of different wavelengths to the target area, blood oxygen saturation information is obtained through multi-wavelength optical imaging technology; and based on the blood oxygen saturation information and the blood flow super-resolution image, a fused image of the target area is obtained by processing and fusion. On the one hand, the fused image is a fused image obtained based on the combination of ultrasound imaging and optical imaging, which has the advantages of high spatial resolution of optical imaging and strong penetration of ultrasound imaging; on the other hand, the fused image not only has the cerebral vascular tissue structure and blood flow information obtained by ultrasound imaging, but also has the blood oxygen saturation information obtained by optical imaging. The fused image provides multi-dimensional information of the cerebral blood vessels, so that it meets the needs of cerebral blood flow detection in terms of time and spatial resolution. The establishment of appropriate physiological and mathematical models can present multi-dimensional information images of brain blood supply including vascular structure, blood flow, and oxygen metabolism at the whole brain level, and realize multi-modal information and image fusion display.

[0111] Example 2

[0112] Based on the dual-mode acoustic imaging method, the present application also provides a dual-mode acoustic imaging system, which is used to execute any step of Example 1.

[0113] like Figure 6 As shown, a dual-mode acoustic imaging system comprises:

[0114] Ultrasonic imaging module 1, used for continuously acquiring multiple frames of ultrasonic images of a target area, filtering the multiple frames of ultrasonic images to extract microbubble images in the multiple frames of ultrasonic images; tracking and processing each microbubble image in the multiple frames of ultrasonic images to obtain a blood flow super-resolution image of the target area;

[0115] The photoacoustic imaging module 2 is used to emit light beams of different wavelengths to the target area to obtain a plurality of photoacoustic images at different wavelengths; the plurality of photoacoustic images are processed based on the spectral absorption characteristics of different substances in the target area to obtain the blood oxygen saturation information of the target area;

[0116] Image fusion module 3 is used to generate blood oxygen metabolism information of the target area based on the blood flow super-resolution image and blood oxygen saturation information; and to perform feature fusion based on the blood oxygen metabolism information and the blood flow super-resolution image to obtain a fused image of the target area. The present application combines the advantages of high spatial resolution of optical imaging and strong penetration of ultrasonic imaging through the coordination between the ultrasonic imaging module, the photoacoustic imaging module and the image fusion module; and the fused image obtained by the coordination of the above modules not only has the cerebral vascular tissue structure and blood flow information obtained by ultrasonic imaging, but also has the blood oxygen saturation information obtained by optical imaging. The fused image provides multi-dimensional information of the cerebral blood vessels, so that it meets the needs of cerebral blood flow detection in terms of time and spatial resolution, and provides important data for characterizing brain nerve / functional activities.

[0117] The ultrasonic imaging module 1 includes: a first processing module 11, which is used to transmit an ultrasonic beam to cover the target area based on the ultrasonic probe, so that the target area returns an ultrasonic echo signal; based on the relative position between the array element of the ultrasonic probe and the target area, the ultrasonic echo signal received by each array element in the ultrasonic probe is delayed; a first superposition module 12, which is used to superimpose each delayed ultrasonic echo signal to obtain an ultrasonic image of the target area. The present application achieves that the complete imaging of the target area can be obtained by transmitting only once through the cooperation of the first processing module and the second processing module, thereby greatly improving the frame rate of ultrasonic imaging, so as to facilitate real-time and accurate observation of the dynamic changes of the target area based on the ultrasonic image.

[0118] The ultrasonic imaging module 1 also includes: a second processing module 13, which is used to delay control the ultrasonic beam of the ultrasonic probe so that the ultrasonic beam of the ultrasonic probe is deflected at a preset deflection angle and scans the target area back and forth; based on the ultrasonic beam of the ultrasonic probe under multiple deflections, multiple images to be processed at different deflection angles are obtained; a second superposition module 14, which is used to superimpose multiple images to be processed at different deflection angles to obtain an ultrasonic image of the target area. The present application deflects the transmitted sound beam at multiple angles through delay control through the cooperation of the second processing module and the second superposition module to obtain multiple images, and superimposes the multiple images to achieve an effect similar to coherent focusing, thereby ensuring that the imaging frame rate reaches more than one thousand frames while greatly improving the imaging quality.

[0119] like Figure 6 As shown, the photoacoustic imaging module 2 includes:

[0120] The photoacoustic image acquisition module 21 is used to sequentially emit light beams of different wavelengths to cover the target area based on the optical signal emitting device, so that the target area returns different ultrasonic echo signals in turn; and acquire multiple photoacoustic images at different wavelengths based on multiple different ultrasonic echo signals and through an image reconstruction algorithm;

[0121] A photoacoustic component extraction module 22, for processing a plurality of photoacoustic images to extract a photoacoustic component corresponding to each photoacoustic image based on the spectral absorption characteristics of the first chromophore substance and the second chromophore substance in the target area;

[0122] The blood oxygen saturation acquisition module 23 is used to generate blood oxygen saturation information of the target area based on the photoacoustic component corresponding to each photoacoustic image, the wavelength of each light beam, the absorption coefficient of the first chromophore substance in the target area, the absorption coefficient of the second chromophore substance in the target area, and the absorption coefficient of the third chromophore substance in the target area; wherein the first chromophore substance includes oxygenated hemoglobin, the second chromophore substance includes deoxygenated hemoglobin, and the third chromophore substance includes other chromophore substances except oxygenated hemoglobin and deoxygenated hemoglobin, such as cytochrome oxidase or melanin.

[0123] The present application realizes highly specific and sensitive quantitative imaging of blood oxygen saturation by using the cooperation among the photoacoustic image acquisition module 21, the photoacoustic component extraction module 22 and the blood oxygen saturation acquisition module 23, based on the different absorption of light by different substances and the different photoacoustic signal intensities, and by using the different photoacoustic spectral characteristics of oxyhemoglobin and deoxyhemoglobin.

[0124] In various embodiments of the present application, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the words listed at the same time. For example, the expression "A or B" or "at least one of A or / and B" may include A, may include B, or may include both A and B.

[0125] The expressions (such as "first", "second", etc.) used in the various embodiments of the present application may modify the various constituent elements in the various embodiments, but may not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only used for the purpose of distinguishing one element from other elements. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, without departing from the scope of the various embodiments of the present application, the first element may be referred to as the second element, and similarly, the second element may also be referred to as the first element.

[0126] It should be noted that in this application, unless otherwise clearly specified and defined, the terms "installation", "connection", "fixation" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0127] In the present application, a person of ordinary skill in the art should understand that the terms indicating orientation or positional relationship herein are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0128] The terms used in the various embodiments of the application are only used to describe the purpose of specific embodiments and are not intended to limit the various embodiments of the application. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise limited, all terms used here (including technical terms and scientific terms) have the same meaning as the meanings commonly understood by ordinary technicians in the field of the various embodiments of the application. The terms (such as the terms defined in the dictionary generally used) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in the various embodiments of the application.

Claims

1. A dual-mode acoustic imaging method, characterized in that: include: Continuously acquiring multiple frames of ultrasound images of the target area, and filtering the multiple frames of ultrasound images to extract microbubble images from the multiple frames of ultrasound images; Tracking each of the microbubble images in multiple frames of ultrasound images to obtain a blood flow super-resolution image of a target area; Emitting light beams of different wavelengths to a target area to obtain a plurality of photoacoustic images at different wavelengths; processing the plurality of photoacoustic images based on spectral absorption characteristics of different substances in the target area to obtain blood oxygen saturation information of the target area; generating blood oxygen metabolism information of a target area based on the blood flow super-resolution image and the blood oxygen saturation information; Feature fusion is performed based on the blood oxygen metabolism information and the blood flow super-resolution image to obtain a fused image of the target area.

2. The dual-mode acoustic imaging method according to claim 1, characterized in that: Each frame of the ultrasound image is obtained by the following steps: Transmitting an ultrasonic beam to cover the target area based on an ultrasonic probe, so that the target area returns an ultrasonic echo signal; Delaying the ultrasonic echo signal received by each array element in the ultrasonic probe based on the relative position between the array element of the ultrasonic probe and the target area; The delayed ultrasonic echo signals are superimposed to obtain the ultrasonic image of the target area.

3. The dual-mode acoustic imaging method according to claim 1, characterized in that: Each frame of the ultrasound image is obtained by the following steps: Delay control of the ultrasonic beam of the ultrasonic probe so that the ultrasonic beam of the ultrasonic probe is deflected at a preset deflection angle and scans the target area back and forth; based on the ultrasonic beam of the ultrasonic probe under multiple deflections, a plurality of images to be processed at different deflection angles are obtained; The multiple images to be processed at different deflection angles are superimposed to obtain the ultrasonic image of the target area.

4. The dual-mode acoustic imaging method according to claim 1, characterized in that: The "filtering the multiple frames of ultrasound images to extract the microbubble images in the multiple frames of ultrasound images; tracking and processing each of the microbubble images in the multiple frames of ultrasound images to obtain a blood flow super-resolution image of the target area" includes: Filtering the multiple frames of ultrasound images through a filter to extract multiple microbubble images from the multiple frames of ultrasound images, each frame of the ultrasound image having at least two microbubble images; Positioning all the microbubble images in each of the ultrasound images to obtain position information of each of the microbubble images; Pairing the microbubble images in two adjacent frames of ultrasound images based on the position information of the microbubble images and the microbubble pairing principle of two adjacent frames of ultrasound images; When a certain microbubble image is paired in multiple consecutive frames of ultrasound images, a microbubble motion trajectory is generated based on the microbubble image; When a preset number of microbubble motion trajectories are acquired, the blood flow super-resolution image is generated based on the preset number of microbubble motion trajectories.

5. The dual-mode acoustic imaging method according to claim 4, characterized in that: The “locating all the microbubble images in each of the ultrasound images to obtain position information of each of the microbubble images” includes: acquiring a point spread function of the microbubble image in the ultrasound image, Acquiring the coordinates of each point of the microbubble image, and determining the point spread function value corresponding to the coordinates of each point of the microbubble image based on the coordinates of each point of the microbubble image and the point spread function; Positioning the microbubble image based on the maximum value of the point spread function values ​​corresponding to the coordinates of each point of the microbubble image to determine the target point coordinates of the microbubble image, and using the target point coordinates of the microbubble image as the position information of the microbubble image; The point coordinates of the microbubble image are expressed as (x, y, z), and the point spread function is expressed as σ x is the full width at half maximum of the point spread function along the x-axis, σ y is the half-maximum full width of the point spread function along the y-axis, σ z is the full width at half maximum of the point spread function along the z-axis, 6. The dual-mode acoustic imaging method according to claim 4, characterized in that: The microbubble pairing principle of two adjacent frames of ultrasound images includes: the sum of distances between multiple groups of paired microbubble images of two adjacent frames of ultrasound images is the smallest; The “pairing each of the microbubble images in two adjacent frames of ultrasound images based on the position information of the microbubble images and the microbubble pairing principle of the two adjacent frames of ultrasound images” includes: Based on the position information of each of the microbubble images in two adjacent frames of the ultrasound image, each of the microbubble images in two adjacent frames of the ultrasound image is paired so that the sum of the distances between multiple groups of paired microbubble images is minimized.

7. The dual-mode acoustic imaging method according to claim 1, characterized in that: The step of "emitting light beams of different wavelengths to the target area" includes: selecting a plurality of light beams of different wavelengths based on a preset wavelength range, wherein the preset wavelength range is between 700 nm and 900 nm; The "emitting light beams of different wavelengths to the target area to obtain a plurality of photoacoustic images at different wavelengths" includes: emitting light beams of different wavelengths in sequence to cover the target area based on the optical signal emitting device, so that the target area returns different ultrasonic echo signals in sequence; and obtaining a plurality of photoacoustic images at different wavelengths based on the plurality of different ultrasonic echo signals and through an image reconstruction algorithm; The “processing the plurality of photoacoustic images based on the spectral absorption characteristics of different substances in the target area to obtain the blood oxygen saturation information of the target area” includes: Based on the spectral absorption characteristics of the first chromophore substance and the second chromophore substance in the target area, processing the plurality of photoacoustic images to extract the photoacoustic component corresponding to each of the photoacoustic images; The blood oxygen saturation information of the target area is generated based on the photoacoustic component corresponding to each of the photoacoustic images, the wavelength of each of the light beams, the absorption coefficient of the first chromophore substance in the target area, the absorption coefficient of the second chromophore substance in the target area, and the absorption coefficient of the third chromophore substance in the target area; wherein the first chromophore substance includes oxygenated hemoglobin, the second chromophore substance includes deoxygenated hemoglobin, and the third chromophore substance includes other chromophore substances except oxygenated hemoglobin and deoxygenated hemoglobin.

8. The dual-mode acoustic imaging method according to claim 1, characterized in that: Also includes: The light beam emitted by the optical signal emitting device is divided into a first light beam and a second light beam by a light beam splitter, and the energy value of the first light beam is equal to the energy value of the second light beam; the first light beam is configured to cover the target area so that the target area returns a photoacoustic echo signal; the second light beam is configured to monitor the energy value of the second light beam by an energy monitoring device, so as to monitor the energy value of the first light beam in real time based on the energy value of the second light beam.

9. A dual-mode acoustic imaging system, characterized in that: include: An ultrasonic imaging module, used for continuously acquiring multiple frames of ultrasonic images of a target area, filtering the multiple frames of ultrasonic images to extract microbubble images in the multiple frames of ultrasonic images; tracking and processing each of the microbubble images in the multiple frames of ultrasonic images to obtain a blood flow super-resolution image of the target area; An optical imaging module, used for emitting light beams of different wavelengths to a target area to obtain a plurality of photoacoustic images at different wavelengths; processing the plurality of photoacoustic images based on the spectral absorption characteristics of different substances in the target area to obtain blood oxygen saturation information of the target area; An image fusion module, used for generating blood oxygen metabolism information of a target area based on the blood flow super-resolution image and the blood oxygen saturation information; Feature fusion is performed based on the blood oxygen metabolism information and the blood flow super-resolution image to obtain a fused image of the target area.

10. The dual-mode acoustic imaging system according to claim 9, characterized in that: The ultrasonic imaging module comprises: A first processing module is used to transmit an ultrasonic beam to cover the target area based on an ultrasonic probe, so that the target area returns an ultrasonic echo signal; based on the relative position between the array element of the ultrasonic probe and the target area, delay the ultrasonic echo signal received by each array element in the ultrasonic probe; A first superposition module, used for superimposing each of the delayed ultrasonic echo signals to obtain the ultrasonic image of the target area; And / or, the ultrasound imaging module comprises: A second processing module is used for delaying the control of the ultrasonic beam of the ultrasonic probe so that the ultrasonic beam of the ultrasonic probe is deflected at a preset deflection angle and scans the target area back and forth; based on the ultrasonic beam of the ultrasonic probe under multiple deflections, a plurality of images to be processed under different deflection angles are obtained; The second superposition module is used to superimpose a plurality of the images to be processed at different deflection angles to obtain the ultrasonic image of the target area.

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