Non-invasive hemodynamic monitoring methods and systems based on photoacoustic-ultrasound imaging

Abstract

This invention relates to the field of biomedical imaging technology and discloses a non-invasive hemodynamic monitoring method and system based on photoacoustic-ultrasound imaging. The method includes: performing non-invasive hemodynamic monitoring based on photoacoustic and ultrasound images, including: obtaining arterial pressure waveforms by analyzing the displacement of arterial vessels or the intensity changes of preset pixels in the photoacoustic or ultrasound image sequence; evaluating venous blood flow velocity by analyzing the inter-frame similarity changes of preset pixel regions in the venous region in the ultrasound image sequence; establishing a dynamic blood flow state by applying external stimulation to the monitored site, and measuring changes in vessel diameter based on the photoacoustic or ultrasound images, and evaluating vessel compliance in conjunction with pressure information. This invention enables non-invasive and integrated monitoring of arterial pressure waveforms, venous blood flow, vessel diameter, and compliance.

Description

Technical Field

[0001] This invention relates to the field of biomedical imaging technology, specifically to a non-invasive hemodynamic monitoring method and system based on photoacoustic-ultrasound imaging. Background Technology

[0002] In the current medical technology context, the measurement of key hemodynamic parameters such as arterial pressure waveforms, venous blood flow, arterial diameter, and compliance still primarily relies on a variety of independent and limited techniques. Arterial pressure waveforms are typically acquired through two approaches: first, invasive arterial catheterization in specific clinical settings. While this method offers high precision, it carries potential risks such as vascular injury, infection, and bleeding, limiting its application in routine monitoring; second, non-invasive devices based on volumetric clamping or pulse contour analysis principles. Although these methods avoid invasive procedures, they are easily affected by factors such as the patient's peripheral circulatory status, limb movement, and local tissue characteristics, impacting the accuracy and stability of the data. Venous blood flow assessment generally relies on Doppler ultrasound imaging. While this technology provides information on blood flow velocity and direction, the results are significantly influenced by the operator's technique and experience, and it is difficult to achieve long-term, continuous monitoring, limiting its application value in dynamically assessing changes in patient condition. In addition, the measurement of arterial diameter and vascular compliance usually requires the use of bioimaging technologies such as ultrasound imaging. This involves dynamically capturing images of changes in vascular diameter with pressure for analysis. Accurately capturing changes in vascular diameter requires high-performance equipment and is easily affected by individual differences and measurement location.

[0003] In summary, existing hemodynamic monitoring technologies generally face challenges in clinical application, including invasive procedures and insufficient multi-parameter monitoring capabilities. These limitations not only restrict their widespread application in various clinical scenarios but also further highlight the urgency and significant value of developing integrated, non-invasive, and continuously monitorable hemodynamic assessment methods. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a non-invasive hemodynamic monitoring method and system based on photoacoustic-ultrasound imaging. It is used to achieve accurate non-invasive monitoring of human hemodynamics. Multi-parameter dynamics include arterial pressure waveform, venous blood flow velocity, vessel diameter, and compliance. This method employs photoacoustic and ultrasound dual-modal imaging technology, overcoming the shortcomings of existing invasive, multi-parameter monitoring capabilities.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a non-invasive hemodynamic monitoring method based on photoacoustic-ultrasound imaging, comprising:

[0007] A photoacoustic signal is generated by exciting the monitored area with a pulsed laser, and a photoacoustic image is acquired and reconstructed.

[0008] Ultrasonic waves are emitted to the monitored area and echo signals are collected to reconstruct an ultrasonic image.

[0009] Based on the photoacoustic and ultrasound images, non-invasive hemodynamic monitoring is performed, including:

[0010] Arterial pressure waveforms are obtained by analyzing the displacement of arterial vessels or the intensity changes of preset pixels in the photoacoustic or ultrasound image sequence.

[0011] Venous blood flow velocity is assessed by analyzing the inter-frame similarity changes of preset pixel regions in the vein region within the ultrasound image sequence.

[0012] By applying external stimulation to the monitored site to establish a dynamic blood flow state, and measuring changes in vessel diameter based on the photoacoustic or ultrasound images, vascular compliance is assessed in conjunction with pressure information.

[0013] In one embodiment, the wavelength of the pulsed laser is 1064 nm.

[0014] In one embodiment, the arterial pressure waveform is obtained by analyzing the displacement of arterial vessels in the photoacoustic or ultrasound image sequence. Specifically, this includes extracting the displacement of arterial vessels in the photoacoustic or ultrasound image using block matching, cross-correlation tracking, optical flow, or vessel segmentation methods, and plotting a curve of arterial vessel displacement over time, thereby achieving monitoring of the arterial pressure waveform.

[0015] In one embodiment, the arterial pressure waveform is obtained by analyzing the intensity changes of preset pixels in the photoacoustic image or ultrasound image sequence. Specifically, this includes: using the image intensity of fixed pixels at the arterial vessel-tissue boundary as the displacement feature of the arterial vessel, and plotting the curve of the displacement feature of the arterial vessel changing over time, thereby realizing the monitoring of the arterial pressure waveform.

[0016] In one embodiment, the step of evaluating venous blood flow velocity by analyzing the inter-frame similarity changes of preset pixel regions in the venous region within the ultrasound image sequence specifically includes:

[0017] The movement of blood cells within veins is represented by changes in the echo intensity of pixels in ultrasound images. By plotting the rate of change of echo intensity in the vein region over time, the velocity of venous blood flow can be monitored.

[0018] In one embodiment, the external stimulus is an ischemia-reperfusion procedure performed via a cuff blood pressure monitor.

[0019] In one embodiment, the assessment of vascular compliance by incorporating pressure information specifically includes: analyzing the ability of blood vessels to expand and rebound under pressure by incorporating changes in vascular pressure, thereby achieving monitoring of vascular compliance.

[0020] In a second aspect, the present invention provides a non-invasive hemodynamic monitoring system based on photoacoustic-ultrasound imaging, for implementing the method of any embodiment of the first aspect, comprising:

[0021] An optical excitation module is used to generate pulsed lasers to excite photoacoustic signals.

[0022] The transducer module is used to acquire photoacoustic signals and to transmit and acquire ultrasonic echo signals.

[0023] The reconstruction processing module is used to reconstruct photoacoustic and ultrasound images based on photoacoustic signals and ultrasound echo signals, and to perform non-invasive hemodynamic monitoring.

[0024] In one embodiment, a water tank is further included for accommodating the coupling medium and immersing the monitored part therein, the transducer module being disposed in the water tank.

[0025] In one embodiment, the monitored part is a human finger; it also includes a cuff blood pressure monitor for applying external stimulation to the limb corresponding to the human finger.

[0026] Compared with the prior art, the beneficial technical effects of the present invention are:

[0027] This invention combines the advantages of photoacoustic imaging and ultrasound imaging, possessing significant characteristics such as high resolution, no ionizing radiation, excellent contrast, high penetration depth, and functional imaging. This enables non-invasive and integrated monitoring of arterial pressure waveforms, venous blood flow, vessel diameter, and compliance. The technology accurately presents arterial pulse waveforms, providing strong support for cardiovascular assessment and arthritis detection. This method also opens up new avenues for assessing vessel diameter, compliance, and venous blood flow velocity, fully demonstrating its enormous potential in preclinical research and clinical translation. Attached Figure Description

[0028] Figure 1 This is a system architecture diagram in an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram illustrating the operation in an embodiment of the present invention.

[0030] Figure 3The images shown are a photoacoustic image of a cross-section of a human finger in an embodiment of the present invention, the corresponding spectrum and fusion image, the time-varying curves of the photoacoustic signals of fixed pixels at the junction of palmar digital vein-tissue and palmar digital artery-tissue, and the spectrum of the photoacoustic signal variation curve of fixed pixels at the junction of artery-tissue.

[0031] Figure 4 The images shown are a photoacoustic image of a cross-section of a human finger in an embodiment of the present invention, and a graph showing the change in photoacoustic intensity of a fixed pixel at the artery-tissue and vein-tissue junction over time during an ischemia-reperfusion experiment.

[0032] Figure 5 The images show an ultrasound image of a cross-section of a human finger in an embodiment of the present invention, and a graph showing the change in inter-frame similarity over time between the venous region and the soft tissue fixation region in an ultrasound image sequence during an ischemia-reperfusion experiment.

[0033] Figure 6 The images shown are photoacoustic images of a cross-section of a human finger and magnified views of the metacarpophalangeal artery at different times in the embodiments of the present invention, as well as graphs showing the changes in the diameter of the metacarpophalangeal artery and the cuff pressure over time.

[0034] Figure 7 This is a flowchart of the method of the present invention.

[0035] In the picture:

[0036] 1: Optical excitation module; 2: Object to be imaged; 3: Transducer module; 4: Reconstruction processing module; 5: Fiber bundle; 6: Water tank. Detailed Implementation

[0037] A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0038] like Figure 7 As shown, a non-invasive hemodynamic monitoring method based on photoacoustic-ultrasound imaging in this invention includes the following steps:

[0039] S1, using pulsed laser to excite the monitored part to generate photoacoustic signal, and then acquiring and reconstructing the photoacoustic image;

[0040] S2, Emit ultrasonic waves to the monitored area and collect echo signals to reconstruct an ultrasonic image;

[0041] S3, based on the photoacoustic and ultrasound images, perform non-invasive hemodynamic monitoring, including:

[0042] S31, obtain the arterial pressure waveform by analyzing the displacement of the arterial vessels or the intensity changes of preset pixels in the photoacoustic image or ultrasound image sequence;

[0043] S32, the venous blood flow velocity is evaluated by analyzing the inter-frame similarity changes of preset pixel regions in the venous region in the ultrasound image sequence;

[0044] S33, by applying external stimulation to the monitored site to establish a dynamic blood flow state, and measuring the change in blood vessel diameter based on the photoacoustic image or ultrasound image, and assessing vascular compliance in combination with pressure information.

[0045] The hemodynamics involved in the monitoring method of the present invention include arterial pressure waveform, venous blood flow velocity, blood vessel diameter, and blood vessel compliance.

[0046] In one embodiment, step S1 specifically includes:

[0047] The optical excitation module outputs pulsed laser light of a specific wavelength to excite the imaged object to generate photoacoustic signals. Simultaneously, the transducer module acquires and digitizes these photoacoustic signals. The reconstruction processing module reads the photoacoustic signal data from the transducer module and reconstructs the photoacoustic image.

[0048] In one embodiment, step S2 specifically includes:

[0049] The transducer module performs ultrasonic transceiver sequences, acquiring and digitizing ultrasonic echo signals. The reconstruction processing module reads the ultrasonic signal data from the transducer module and reconstructs the ultrasonic image.

[0050] In one embodiment, step S3 specifically includes:

[0051] Monitoring of Arterial Pressure Waveforms: Since heartbeats cause fluctuations in arterial pressure, arteries exhibit corresponding pulsations and displacements, and these displacements are closely related to the trend of arterial pressure. In photoacoustic or ultrasound images, displacement parameters of arteries can be extracted using methods such as block matching, cross-correlation tracking, optical flow, and vessel segmentation. Furthermore, monitoring the intensity changes of fixed pixels at the arterial vessel-tissue boundary can also reflect the displacement characteristics of the arteries. This is because, under the influence of arterial displacement, the imaged object corresponding to that pixel switches back and forth between tissue and blood, resulting in continuous changes in image intensity. By plotting curves showing the changes in arterial vessel displacement or its characteristics over time, monitoring of arterial pressure waveforms can be achieved.

[0052] Monitoring venous blood flow velocity: In ultrasound images, a fixed pixel region at the location of the blood vessel is selected for observation. Because blood vessels contain flowing blood and blood cells, the movement of these cells appears as moving echoes with higher intensity than the blood background in the ultrasound image. By monitoring the rate of change of these echoes over time, the blood flow velocity within that pixel region can be indirectly reflected. For example, blood flow velocity can be assessed by calculating the similarity of this pixel region between different frames in an ultrasound image sequence. Higher similarity between adjacent frames indicates slower blood cell movement, i.e., slower venous blood flow velocity; conversely, lower similarity between adjacent frames indicates faster blood cell movement, i.e., faster venous blood flow velocity. By plotting the rate of change of venous echoes over time, the characteristics of venous blood flow velocity can be monitored.

[0053] Monitoring of vessel diameter and compliance: A dynamic blood flow state (e.g., alternation between ischemia and reperfusion) is established at the monitored vessel site through external stimuli (such as ischemia-reperfusion experiments). Vessel diameter is measured using photoacoustic or ultrasound imaging, and a curve showing the change in vessel diameter over time is plotted, thus enabling vessel diameter monitoring. By combining this with changes in vascular pressure, the vessel's ability to expand and rebound under pressure is analyzed, thereby enabling monitoring of vascular compliance.

[0054] Example:

[0055] like Figure 1 and Figure 2 As shown, the system used in this embodiment includes an optical excitation module 1, an imaged object 2, a transducer module 3, a reconstruction processing module 4, an optical fiber bundle 5, a water tank 6, and a cuff blood pressure monitor, etc.

[0056] The optical excitation module is used to generate pulsed lasers, which excite the imaged object to produce ultrasonic waves through the photoacoustic effect. These ultrasonic waves are also known as photoacoustic signals.

[0057] The transducer module is used to acquire and digitize photoacoustic signals, and also to transmit, acquire, and digitize ultrasonic signals;

[0058] The reconstruction processing module is used to reconstruct the original photoacoustic and ultrasound signal data into photoacoustic and ultrasound images, and to perform non-invasive hemodynamic monitoring, analysis and visualization.

[0059] Fiber optic bundles are used to deliver pulsed laser light to the object being imaged.

[0060] The water tank is used for acoustic coupling between the object being imaged and the transducer module.

[0061] Cuff blood pressure monitors are used for human ischemia-reperfusion experiments and for monitoring blood pressure during the experiments.

[0062] This embodiment adopts Figure 2 The method shown is used for non-invasive hemodynamic monitoring of human fingers, mainly monitoring arterial waveforms under normal conditions, monitoring arterial pressure waveforms during ischemia-reperfusion experiments, monitoring venous blood flow velocity, and monitoring arterial diameter and vascular compliance.

[0063] The specific process of this embodiment is as follows:

[0064] (1) Place human fingers in the transducer module and fill the space between the human fingers and the transducer module with water to ensure acoustic coupling between the fingers and the transducer module.

[0065] (2) Photoacoustic imaging. The optical excitation module outputs a 1064nm pulsed laser to excite the human finger to generate a photoacoustic signal. At the same time, the transducer module completes the acquisition and digitization of the photoacoustic signal. The reconstruction processing module reads the photoacoustic signal data and reconstructs the photoacoustic image.

[0066] (3) Ultrasonic imaging. The transducer module performs ultrasonic transceiver and acquires and digitizes ultrasonic echoes. The reconstruction processing module reads the ultrasonic echo signal data and reconstructs the ultrasonic image.

[0067] (4) Monitoring of arterial pressure waveform under normal conditions. A pixel at the palmar digital artery-tissue boundary was selected in the two-dimensional photoacoustic image, and the curve of the photoacoustic signal changing over time at this fixed pixel was plotted. This curve reflects the arterial pressure waveform. Fourier transform analysis was performed on this time-domain curve to analyze its frequency domain information. The results are as follows: Figure 3 .

[0068] (5) Ischemia-reperfusion test. A cuff is installed on the forearm of the human body, and the cuff pressure is manually controlled by inflation and deflation. When the cuff pressure exceeds about 40-50 mmHg, venous return will weaken or stop; when the cuff pressure is greater than the test subject's systolic blood pressure, arterial blood ejection will weaken or stop. This allows for the control of ischemia and reperfusion in the fingertips. The state before the cuff is inflated is defined as the baseline state. The cuff pressure is continuously increased, and when the cuff pressure is greater than the test subject's systolic blood pressure, it is defined as the occlusion stage. When the cuff is released, and the cuff pressure begins to be less than the test subject's systolic blood pressure, it is defined as the reperfusion stage.

[0069] (6) Monitoring of arterial pressure waveforms during ischemia-reperfusion experiments. Pixels at the arterial-tissue boundary were selected in the two-dimensional photoacoustic image, and the change curve of the photoacoustic signal at this fixed pixel point over time was plotted. The results are as follows: Figure 4 .

[0070] (7) Monitoring of venous blood flow velocity under ischemia-reperfusion experiment. An ischemia-reperfusion experiment was conducted. A venous pixel region was selected in the ultrasound image, and the inter-frame similarity curve of the ultrasound image of this fixed pixel region was plotted over time. The results are shown below. Figure 5 .

[0071] (8) Monitoring of vessel diameter and compliance under ischemia-reperfusion experiment. An ischemia-reperfusion experiment was conducted. The diameter of the arterial vessels was measured in the photoacoustic image, and a curve showing the change of the arterial vessel diameter over time was plotted. Pixels at the arterial and venous locations were selected in the photoacoustic image, and curves showing the change of normalized photoacoustic intensity over time at the arterial and venous locations were plotted separately. Figure 6 .

[0072] The results of this embodiment can be found in [link / reference]. Figures 3 to 6 .

[0073] Figure 3 Image 'a' in the image shows a photoacoustic image of a cross-section of a human finger, a spectrogram based on fast Fourier transform, and a fused image of the two. Anatomical structures such as the dorsal digital vein, palmar digital vein, and palmar digital artery are clearly visible. Figure 3 In the figure, 'b' represents the photoacoustic signal variation curve of a fixed pixel at the junction of the palmar digital vein-tissue and the palmar digital artery-tissue, over time. It can be seen that the photoacoustic signal of the fixed pixel at the artery-tissue junction exhibits periodic changes driven by the heartbeat, reflecting the waveform of arterial pressure. The photoacoustic signal of the fixed pixel at the vein-tissue junction, however, is relatively stable. By selecting one cardiac cycle from the photoacoustic signal variation curve of the fixed pixel at the artery-tissue junction, the rising systolic segment (T1), the falling systolic segment (T2), the dicrotic notch (T3), and the diastolic outflow segment (T4) can be distinguished. Figure 3 c in Figure 3 The spectrum of the photoacoustic signal change curve of the fixed pixel at the arterial-tissue junction in b can be used to distinguish the human heart rate as 1.4 Hz (84 beats / minute). The presence of the second and third harmonics reflects the asymmetrical waveform characteristics of arterial pulsation, which in the time domain are a rapid rise in the systolic phase and a gradual decay in the diastolic phase.

[0074] Figure 4 Image 'a' in the image shows a photoacoustic image of a cross-section of a human finger. Figure 4 Figure b shows the photoacoustic intensity curves of fixed pixels at the arterial-tissue and vein-tissue junctions over time during the ischemia-reperfusion experiment. At the baseline, arterial pressure fluctuations can be seen normally. During the occlusion, the arterial pulsation disappears because the cuff pressure is greater than the body's systolic blood pressure. During the reperfusion period after the cuff is released, the arterial pulsation recovers, while the photoacoustic intensity of fixed pixels at the vein-tissue junction remains relatively stable.

[0075] Figure 5 Image 'a' in the diagram shows an ultrasound image of a cross-section of a human finger. Figure 5Figure b illustrates the change in inter-frame similarity over time between the venous region and the soft tissue fixation region in the ultrasound image sequence during the ischemia-reperfusion experiment. Since a higher SSIM value (between 0 and 1) corresponds to lower blood flow velocity, the inter-frame similarity of the venous region is less than 1 at baseline due to the presence of blood flow in the vein, while the inter-frame similarity of the soft tissue region is approximately 1. During occlusion, venous return weakens or disappears, and the inter-frame similarity of the venous region increases, indicating a slowdown in venous blood flow velocity. During reperfusion after cuff release, venous blood flow recovers, and reactive hyperemia causes a transient overshoot in blood flow velocity, manifested as a rapid initial drop in inter-frame similarity to a low value, followed by a return to baseline levels.

[0076] Figure 6 Image 'a' in the diagram shows a photoacoustic image of a cross-section of a human finger and magnified views of the metacarpophalangeal arteries at different times (T1, T2, T3, T4, T5, T6). Figure 6 Mark the 'b' in the text. Figure 6 b in the image shows the metacarpophalangeal artery ( Figure 6 The changes in diameter and cuff pressure over time are shown within the black dashed box (a) in the diagram. During the occlusion phase, the palmar digital arteries constrict by approximately 8% due to decreased arterial pressure. The vessel diameter stabilizes approximately 10 seconds after occlusion. Notably, about 25 seconds after occlusion, although the cuff pressure remains higher than the systolic pressure, the arteries begin to dilate prematurely, indicating that reactive vasodilation driven by local metabolic stress and mediated by endothelial mechanisms has begun early. Upon cuff release, reperfusion and reactive hyperemia rapidly establish themselves, further enhancing vasodilation and increasing the arterial diameter by approximately 14% from baseline. About 15 seconds after reperfusion, the arteries begin to constrict and gradually return to baseline levels, marking the end of the metabolically driven vasodilation and hyperemia response.

[0077] Figure 6 c in the diagram shows another metacarpophalangeal artery and metacarpophalangeal vein ( Figure 6The changes in photoacoustic intensity and cuff pressure over time at the location indicated by the white arrow (a) show that the photoacoustic intensity of the metacarpophalangeal arteries exhibits a similar trend to the change in the diameter of the metacarpophalangeal arteries, while the photoacoustic intensity of the metacarpophalangeal veins shows the opposite pattern. Specifically, because a cuff pressure of approximately 40-50 mmHg hinders venous return, venous return begins to stagnate after about 15 seconds, while arterial ejection continues, causing the venous photoacoustic intensity to gradually increase by about 7%. When the cuff pressure exceeds the systolic pressure, arterial ejection weakens, and the venous photoacoustic intensity tends to stabilize. When the cuff pressure is released to approximately 80-90 mmHg, arterial ejection and venous return resume. Due to the accelerated outflow of accumulated blood for rapid clearance, the venous photoacoustic intensity temporarily drops below the baseline value by about 22%, while the arterial photoacoustic intensity shows a transient overshoot. Compared to the arterial response, the slower recovery of the veins may reflect limited active regulatory capacity and increased susceptibility to passive blood retention and delayed clearance, reflecting the difference in compliance between arteries and veins.

[0078] In summary, this method, based on photoacoustic-ultrasound imaging, achieves complete monitoring of arterial pressure waveforms in the human finger, reflecting specific stages of the cardiac cycle and heart rate. By altering the cuff pressure in the upper limb, the ischemia and reperfusion phases of the fingertip are established, providing a complete dynamic monitoring of arterial pressure waveforms, venous blood flow, arterial diameter, and venous and arterial compliance during these phases. This method achieves non-invasive hemodynamic monitoring, providing a powerful tool for assessing vascular response, metabolic regulation, and pathophysiological changes, and offering crucial insights for cardiovascular research and related translational applications.

[0079] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0080] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some of the steps in the flowcharts of the accompanying drawings may include multiple steps or stages, which are not necessarily completed at the same time, but may be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but may be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0081] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0083] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A non-invasive hemodynamic monitoring method based on photoacoustic-ultrasound imaging, characterized in that, include: A photoacoustic signal is generated by exciting the monitored area with a pulsed laser, and a photoacoustic image is acquired and reconstructed. Ultrasonic waves are emitted to the monitored area and echo signals are collected to reconstruct an ultrasonic image. Based on the photoacoustic and ultrasound images, non-invasive hemodynamic monitoring is performed, including: Arterial pressure waveforms are obtained by analyzing the displacement of arterial vessels or the intensity changes of preset pixels in the photoacoustic or ultrasound image sequence. Venous blood flow velocity is assessed by analyzing the inter-frame similarity changes of preset pixel regions in the vein region within the ultrasound image sequence. By applying external stimulation to the monitored site to establish a dynamic blood flow state, and measuring changes in vessel diameter based on the photoacoustic or ultrasound images, vascular compliance is assessed in conjunction with pressure information.

2. The non-invasive hemodynamic monitoring method based on photoacoustic-ultrasound imaging according to claim 1, characterized in that, The wavelength of the pulsed laser is 1064 nm.

3. The non-invasive hemodynamic monitoring method based on photoacoustic-ultrasound imaging according to claim 1, characterized in that, Arterial pressure waveforms are obtained by analyzing the displacement of arterial vessels in the photoacoustic or ultrasound image sequence. Specifically, this includes extracting the displacement of arterial vessels in the photoacoustic or ultrasound image using block matching, cross-correlation tracking, optical flow, or vessel segmentation methods, and plotting the curve of arterial vessel displacement over time, thereby achieving monitoring of arterial pressure waveforms.

4. The non-invasive hemodynamic monitoring method based on photoacoustic-ultrasound imaging according to claim 1, characterized in that, Arterial pressure waveforms are obtained by analyzing the intensity changes of preset pixels in the photoacoustic or ultrasound image sequence. Specifically, this includes using the image intensity of fixed pixels at the arterial vessel-tissue boundary as the displacement feature of the arterial vessel, and plotting the curve of the displacement feature of the arterial vessel over time, thereby realizing the monitoring of arterial pressure waveforms.

5. The non-invasive hemodynamic monitoring method based on photoacoustic-ultrasound imaging according to claim 1, characterized in that, The method of evaluating venous blood flow velocity by analyzing the inter-frame similarity changes of preset pixel regions in the venous region within the ultrasound image sequence specifically includes: The movement of blood cells within veins is represented by changes in the echo intensity of pixels in ultrasound images. By plotting the rate of change of echo intensity in the vein region over time, the velocity of venous blood flow can be monitored.

6. The non-invasive hemodynamic monitoring method based on photoacoustic-ultrasound imaging according to claim 1, characterized in that, The external stimulus is an ischemia-reperfusion procedure performed via a cuff blood pressure monitor.

7. The non-invasive hemodynamic monitoring method based on photoacoustic-ultrasound imaging according to claim 1, characterized in that, The assessment of vascular compliance by incorporating pressure information specifically includes: analyzing the ability of blood vessels to expand and rebound under pressure by combining changes in vascular pressure, thereby enabling the monitoring of vascular compliance.

8. A non-invasive hemodynamic monitoring system based on photoacoustic-ultrasound imaging, used to implement the method as described in any one of claims 1 to 7, characterized in that, include: An optical excitation module is used to generate pulsed lasers to excite photoacoustic signals. The transducer module is used to acquire photoacoustic signals and to transmit and acquire ultrasonic echo signals. The reconstruction processing module is used to reconstruct photoacoustic and ultrasound images based on photoacoustic signals and ultrasound echo signals, and to perform non-invasive hemodynamic monitoring.

9. The system according to claim 8, characterized in that, It also includes a water tank for accommodating the coupling medium and immersing the monitored part therein, wherein the transducer module is disposed in the water tank.

10. The system according to claim 8, characterized in that, The monitored area is the human finger; it also includes a cuff blood pressure monitor for applying external stimulation to the limb corresponding to the human finger.

Images