Large-view-field high-dynamic myocardial blood flow rate imaging method and device

Abstract

The invention provides a large-field-of-view high-dynamic myocardial blood flow rate imaging method and device, and relates to the technical field of biomedical optical imagines.The method comprises the steps that imaging parameters of an imaging unit are optimized according to a preset optimization strategy, and the optimized imaging unit is used for collecting laser speckle images of an observation area; a plurality of laser speckle images are obtained; and determining a space speckle contrast matrix and a time speckle contrast matrix of the observation area based on the plurality of laser speckle images, and generating a blood flow index distribution image of the observation area based on the space speckle contrast matrix and the time speckle contrast matrix. According to the large-view-field high-dynamic myocardial blood flow rate imaging method and device, through multi-parameter optimization, the signal-to-noise ratio of myocardial blood flow imaging and the measurable range of the blood flow rate can be effectively increased, and the problem that the myocardial blood flow imaging area is limited is solved.

Description

Technical Field

[0001] This application relates to the field of biomedical optical imaging technology, and particularly to a large field of view and high dynamic myocardial blood flow rate imaging method and device. Background Art

[0002] Laser speckle contrast imaging technology has been widely used in the monitoring of blood flow rate distribution in organs such as the brain, skin, retina, and kidney due to its advantages of wide-field imaging, high spatio-temporal resolution, non-contact, green and non-toxic, and simple device. Its principle depends on the quantitative effect relationship between laser speckle contrast and blood flow rate index, and this quantitative effect relationship is affected by the normalization factor of the hardware system, the proportion coefficient of static scattering components, and the scattering type of the interaction between laser and blood cells. These parameters directly determine the blood flow rate measurement sensitivity, the measurable range of the rate, and the imaging time / space resolution of blood flow distribution.

[0003] In related technologies, through laser speckle contrast imaging technology, retinal and skin blood flow speckle imaging has been realized, the evaluation range and sensitivity of blood flow rate have been improved by establishing a multiple exposure speckle imaging model, and the accuracy of cerebral cortex blood flow measurement has been improved by establishing a dynamic scattered light imaging model.

[0004] However, the above technical solutions in related technologies are only applicable to small windows and microscopic imaging of low blood flow rates in small veins such as the cerebral cortex, retina, and kidney on the surface or shallow surface under simple and stable environments, and cannot be applied to the imaging of high dynamic myocardial blood flow rate, resulting in problems such as low signal-to-noise ratio of myocardial blood flow rate imaging, small measurable range of myocardial blood flow rate, and limited myocardial blood flow imaging area. Summary of the Invention

[0005] The purpose of this application is to provide a large field of view and high dynamic myocardial blood flow rate imaging method and device, which can effectively improve the signal-to-noise ratio of myocardial blood flow imaging and the measurable range of blood flow rate through multi-parameter optimization, and solve the problem of limited myocardial blood flow imaging area.

[0006] This application provides a large field of view and high dynamic myocardial blood flow rate imaging method, including: Optimizing the imaging parameters of the imaging unit according to a preset optimization strategy, and using the optimized imaging unit to collect laser speckle images of the observation area to obtain a plurality of laser speckle images; determining the spatial speckle contrast matrix and the temporal speckle contrast matrix of the observation area based on the plurality of laser speckle images, and generating a blood flow index distribution image of the observation area based on the spatial speckle contrast matrix and the temporal speckle contrast matrix; wherein, the preset optimization strategy includes at least one of the following: camera imaging field of view size optimization strategy, speckle image average intensity optimization strategy, exposure time optimization strategy, and camera gain optimization strategy.

[0007] Optionally, optimizing the imaging parameters of the imaging unit according to the preset optimization strategy includes: optimizing the camera shooting parameters of the imaging unit according to the camera imaging field size optimization strategy; wherein, the camera imaging field size optimization strategy includes: the dark field noise of the camera is less than or equal to 2.5e-1, the quantum efficiency of the infrared band of the camera is greater than or equal to 30%, the acquisition frame rate range of the camera is: greater than or equal to 60 Hz and less than or equal to 100 Hz, the pixel size of the camera is less than or equal to 3.45 microns, the pixel number range of the camera is: greater than or equal to 1.5 million pixels and less than or equal to 1.6 million pixels, and the magnification range of the imaging lens of the camera is: greater than or equal to 0.3 times and less than or equal to 0.45 times, so that the difference between the size ratio of the laser speckle size to the camera pixel size and 1 is minimized.

[0008] Optionally, optimizing the imaging parameters of the imaging unit according to the preset optimization strategy includes: optimizing the camera shooting parameters of the imaging unit according to the speckle image average intensity optimization strategy; wherein, the speckle image average intensity optimization strategy includes: the average gray level of the speckle image is greater than or equal to 1 / 4 of the saturation gray level value and less than or equal to 1 / 2 of the saturation gray level value.

[0009] Optionally, optimizing the imaging parameters of the imaging unit according to the preset optimization strategy includes: optimizing the camera shooting parameters of the imaging unit according to the exposure time optimization strategy; wherein, the exposure time optimization strategy includes: when the measurement object is the blood flow rate of a phantom, the exposure time of the camera is: greater than or equal to 50 microseconds and less than or equal to 100 microseconds; when the measurement object is the blood flow rate of a living animal, the exposure time of the camera is: greater than or equal to 500 microseconds and less than or equal to 1000 microseconds.

[0010] Optionally, optimizing the imaging parameters of the imaging unit according to the preset optimization strategy includes: optimizing the camera shooting parameters of the imaging unit according to the camera gain optimization strategy; wherein, the camera gain optimization strategy includes: when the measurement object is the blood flow rate of a phantom, the camera gain is: greater than or equal to 0 dB and less than or equal to 10 dB; when the measurement object is the blood flow rate of a living animal, the camera gain is: greater than or equal to 8 dB and less than or equal to 20 dB.

[0011] Optionally, the blood flow rate imaging system further includes: a laser illumination unit; the illumination wavefront generated by the laser illumination unit is: a flat-top beam wavefront; the two imaging units are inclined along the central positions of the two imaging units and the angle with the horizontal direction is less than or equal to 10°.

[0012] Optionally, based on the multiple laser speckle images, determining a spatial speckle contrast matrix and a temporal speckle contrast matrix of the observation region, and generating a blood flow index distribution image of the observation region based on the spatial speckle contrast matrix and the temporal speckle contrast matrix, includes: obtaining system coherence parameters, and determining a dynamic scattering component proportion coefficient of the observation region according to the system coherence parameters, the spatial speckle contrast matrix, and the temporal speckle contrast matrix; determining a blood flow index matrix of the observation region according to the system coherence parameters, the spatial speckle contrast matrix, the temporal speckle contrast matrix, and the dynamic scattering component proportion coefficient; and generating a blood flow index distribution image of the observation region according to the blood flow index matrix.

[0013] The present application further provides a large field of view and high dynamic myocardial blood flow velocity imaging device, including: A parameter setting module, configured to optimize imaging parameters of an imaging unit according to a preset optimization strategy; an image acquisition module, configured to use the optimized imaging unit to acquire laser speckle images of an observation region, obtaining a plurality of laser speckle images; an image generation module, configured to determine a spatial speckle contrast matrix and a temporal speckle contrast matrix of the observation region based on the plurality of laser speckle images, and generate a blood flow index distribution image of the observation region based on the spatial speckle contrast matrix and the temporal speckle contrast matrix; wherein the preset optimization strategy includes at least one of the following: a camera imaging field of view size optimization strategy, a speckle image average intensity optimization strategy, an exposure time optimization strategy, and a camera gain optimization strategy.

[0014] Optionally, the parameter setting module is specifically configured to optimize camera shooting parameters of the imaging unit according to the camera imaging field of view size optimization strategy; wherein the camera imaging field of view size optimization strategy includes: the dark field noise of the camera is less than or equal to 2.5e -1 , the quantum efficiency of the infrared band of the camera is greater than or equal to 30%, the acquisition frame rate range of the camera is: greater than or equal to 60 Hz and less than or equal to 100 Hz, the pixel size of the camera is less than or equal to 3.45 microns, the pixel number range of the camera is: greater than or equal to 1.5 million pixels and less than or equal to 1.6 million pixels, and the magnification range of the imaging lens of the camera is: greater than or equal to 0.3 times and less than or equal to 0.45 times, so that the difference between the ratio of the laser speckle size to the camera pixel size and 1 is minimized.

[0015] Optionally, the parameter setting module is specifically configured to optimize the camera shooting parameters of the imaging unit according to the speckle image average intensity optimization strategy; wherein, the speckle image average intensity optimization strategy includes: the average gray scale of the speckle image is greater than or equal to 1 / 4 of the saturation gray scale value and less than or equal to 1 / 2 of the saturation gray scale value.

[0016] Optionally, the parameter setting module is specifically configured to optimize the camera shooting parameters of the imaging unit according to the exposure time optimization strategy; wherein, the exposure time optimization strategy includes: when the measurement object is the blood flow rate of a phantom, the exposure time of the camera is greater than or equal to 50 microseconds and less than or equal to 100 microseconds; when the measurement object is the blood flow rate of a living animal, the exposure time of the camera is greater than or equal to 500 microseconds and less than or equal to 1000 microseconds.

[0017] Optionally, the parameter setting module is specifically configured to optimize the camera shooting parameters of the imaging unit according to the camera gain optimization strategy; wherein, the camera gain optimization strategy includes: when the measurement object is the blood flow rate of a phantom, the camera gain is greater than or equal to 0 dB and less than or equal to 10 dB; when the measurement object is the blood flow rate of a living animal, the camera gain is greater than or equal to 8 dB and less than or equal to 20 dB.

[0018] Optionally, the blood flow rate imaging system further includes: a laser illumination unit; the illumination wavefront generated by the laser illumination unit is: a flat-top beam wavefront; the two imaging units are inclined along the central positions of the two imaging units and the included angle with the horizontal direction is less than or equal to 10°.

[0019] Optionally, the image generation module is specifically configured to obtain system coherence parameters, and determine the dynamic scattering component proportion coefficient of the observation area according to the system coherence parameters, the spatial speckle contrast matrix, and the temporal speckle contrast matrix; the image generation module is specifically further configured to determine the blood flow index matrix of the observation area according to the system coherence parameters, the spatial speckle contrast matrix, the temporal speckle contrast matrix, and the dynamic scattering component proportion coefficient; the image generation module is specifically further configured to generate a blood flow index distribution image of the observation area according to the blood flow index matrix.

[0020] This application also provides a computer program product, including computer programs / instructions, which when executed by a processor implement the steps of the large field of view high dynamic myocardial blood flow rate imaging method as described in any one of the above.

[0021] The present application also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the large field of view high-dynamic myocardial blood flow rate imaging method as described in any one of the above are implemented.

[0022] The present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the large field of view high-dynamic myocardial blood flow rate imaging method as described in any one of the above are implemented.

[0023] For the large field of view high-dynamic myocardial blood flow rate imaging method and device provided by the present application, first, the imaging parameters of the imaging unit are optimized according to a preset optimization strategy, and the optimized imaging unit is used to collect laser speckle images of the observation area to obtain a plurality of laser speckle images; then, based on the plurality of laser speckle images, a spatial speckle contrast matrix and a temporal speckle contrast matrix of the observation area are determined, and a blood flow index distribution image of the observation area is generated based on the spatial speckle contrast matrix and the temporal speckle contrast matrix; wherein, the preset optimization strategy includes at least one of the following: camera imaging field of view size optimization strategy, speckle image average intensity optimization strategy, exposure time optimization strategy, and camera gain optimization strategy. In this way, the signal-to-noise ratio of myocardial blood flow imaging and the measurable range of blood flow rate can be effectively improved, and the problem of limited myocardial blood flow imaging area can be solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0025] Figure 1 is a schematic diagram of the system architecture of the myocardial blood flow rate imaging method provided by the present application; Figure 2 is a schematic flowchart of the large field of view high-dynamic myocardial blood flow rate imaging method provided by the present application; Figure 3 is a schematic diagram of the influence of the camera acquisition frame rate on myocardial blood flow rate imaging provided by the present application; Figure 4 is a schematic diagram of the influence of the ratio of the speckle size to the pixel size on the linear range of laser speckle blood flow measurement provided by the present application; Figure 5 is a schematic diagram of the influence of the exposure time of the phantom experiment on the blood flow rate measurement range provided by the present application; Figure 6It is one of the schematic structural diagrams of the laser illumination unit provided by the present application; Figure 7 It is the second of the schematic diagrams of the influence of the laser illumination unit provided by the present application; Figure 8 It is the schematic structural diagram of the blood flow rate imaging system provided by the present application; Figure 9 It is the schematic structural diagram of the large field of view and high dynamic myocardial blood flow rate imaging device provided by the present application; Figure 10 It is the schematic structural diagram of the electronic device provided by the present application. Detailed implementation manners

[0026] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below with reference to the accompanying drawings in the present application. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art without making creative efforts based on the embodiments in the present application belong to the scope of protection of the present application.

[0027] The terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that such used data may be interchanged under appropriate circumstances so that the embodiments of the present application can be implemented in an order different from those illustrated or described herein, and the objects distinguished by "first", "second", etc. generally belong to the same category, and the number of objects is not limited. For example, the first object may be one or more. In addition, "and / or" in the description and claims means at least one of the connected objects, and the character " / " generally means an "or" relationship between the related objects before and after.

[0028] Aiming at the problems of low signal-to-noise ratio of myocardial blood flow imaging, small measurable range of blood flow rate, and limited myocardial blood flow imaging area in the related art, the embodiments of the present application provide a large field of view and high dynamic myocardial blood flow rate imaging method. As Figure 1 shown, this method optimizes the camera imaging field of view size, imaging lens parameters, the ratio of speckle size to pixel size, laser illumination wavefront, average intensity of speckle images, exposure time, camera gain, and the laser speckle-blood flow rate theoretical model, aiming to solve the problems of low signal-to-noise ratio of myocardial blood flow imaging, small measurable range of blood flow rate, and limited size of the myocardial blood flow imaging area.

[0029] The following will, with reference to the accompanying drawings, elaborate on the large field of view and high dynamic myocardial blood flow rate imaging method provided by the embodiments of the present application through specific embodiments and their application scenarios.

[0030] As Figure 2 shown, a large field of view and high dynamic myocardial blood flow rate imaging method provided by an embodiment of the present application may include the following steps 201 and 202: Step 201: Optimize the imaging parameters of the imaging unit according to a preset optimization strategy, and use the optimized imaging unit to collect laser speckle images of an observation area to obtain a plurality of laser speckle images.

[0031] The preset optimization strategy includes at least one of the following: a camera imaging field of view size optimization strategy, a speckle image average intensity optimization strategy, an exposure time optimization strategy, and a camera gain optimization strategy.

[0032] Specifically, in the above step 201, for the step of the camera imaging field of view size optimization strategy, the following step 201a may further be included: Step 201a: Optimize the camera shooting parameters of the imaging unit according to the camera imaging field of view size optimization strategy.

[0033] The camera imaging field of view size optimization strategy includes: the dark field noise of the camera is less than or equal to 2.5e -1 , the quantum efficiency of the infrared band of the camera is greater than or equal to 30%, the acquisition frame rate range of the camera is: greater than or equal to 60 Hz and less than or equal to 100 Hz, the pixel size of the camera is less than or equal to 3.45 microns, the pixel number range of the camera is: greater than or equal to 1.5 million pixels and less than or equal to 1.6 million pixels, and the magnification range of the imaging lens of the camera is: greater than or equal to 0.3 times and less than or equal to 0.45 times, so that the difference between the size ratio of the laser speckle size to the camera pixel size and 1 is minimized.

[0034] Exemplarily, according to the clinical requirements of an imaging size of about 15 mm×15 mm in the distal region of coronary artery stenosis, equipment cost, and the characteristics of biological weak light imaging, a large field of view imaging is achieved by adopting a double-camera and double-lens splicing method. The camera imaging field of view size is determined by the camera sensor size (the product of the pixel number and the pixel size) and the imaging lens magnification. At the same time, the imaging lens magnification also determines the average laser speckle size on the camera sensor surface.

[0035] Exemplarily, when the ratio of the laser speckle size to the pixel size is about 1, spatial speckle integration can be effectively avoided, and then more accurate laser speckle spatial statistical characteristics can be obtained, so that the laser speckle hardware system has a better large dynamic and linear rate measurement range. Therefore: for biological weak light imaging and the strong scattering characteristics of biological tissues, it is required that the camera dark field noise is not greater than 2.5e -1 , and the quantum efficiency in the near-infrared band is not less than 30%.

[0036] Exemplarily, asFigure 3 As shown, appropriately increasing the acquisition frame rate can effectively suppress the interference of vibration environmental noise. The camera acquisition frame rate is required to be 60 Hz - 100 Hz (Hertz); after confocal microscope detection, the diameter of red blood cells is about 6.5 μm - 9 μm (micrometer). Theoretically speaking, the smaller the magnification of the imaging lens, the easier it is to meet the requirements of the imaging field of view size, and even the splicing of two cameras and two lenses is not required. However, considering the above limitation that "the ratio of the speckle size to the pixel size is about 1", the smaller the magnification of the imaging lens, the smaller the pixel size and the higher the number of pixels are required. Weighing the camera performance and cost, while meeting the requirements of low dark field noise, relatively high quantum efficiency and high acquisition frame rate, the optimal choice for the pixel size is 3.45 μm, or not greater than 3.45 μm, the optimal choice for the number of pixels is 1.5 - 1.6 million pixels, and the optimal choice range for the magnification of the imaging lens is 0.3X - 0.45X (times). As Figure 4 shown, it is a schematic diagram of the influence of the ratio of the speckle size to the pixel size on the linear range of laser speckle blood flow measurement.

[0037] Specifically, in the above step 201, for the steps of the speckle image average intensity optimization strategy, the following step 201b can also be included: Step 201b: Optimize the camera shooting parameters of the imaging unit according to the speckle image average intensity optimization strategy.

[0038] Among them, the speckle image average intensity optimization strategy includes: the average gray level of the speckle image is greater than or equal to 1 / 4 of the saturation gray level value and less than or equal to 1 / 2 of the saturation gray level value.

[0039] Exemplarily, the gray level dynamic range of the camera sensor is limited, mainly including 8-bit (bit), 10-bit and 12-bit. The characteristic that the laser speckles are randomly distributed in bright and dark easily causes the light intensity received by some pixels to exceed the upper limit of its dynamic range. For example, pixels receiving light intensity greater than 100 mW all show a gray level value of 255 (8-bit), that is, the fluctuation characteristics of the speckle spots with light intensity greater than 100 mW will be submerged. According to K = σI / , the speckle contrast value will be smaller than the true value, resulting in inaccurate experimental results. To avoid this problem, the optimal range of the average gray value of the speckle image is set as: not less than 1 / 4 of the saturation gray value and not greater than 1 / 2 of the saturation gray value. Taking an 8-bit camera as an example, the average gray value of the recorded speckle image is not greater than 128 and not less than 60.

[0040] Specifically, in the above step 201, for the steps of the exposure time optimization strategy, the following step 201c may further be included: Step 201c: Optimize the camera shooting parameters of the imaging unit according to the exposure time optimization strategy.

[0041] Among them, the exposure time optimization strategy includes: when the measurement object is the blood flow rate of a phantom, the exposure time of the camera is greater than or equal to 50 microseconds and less than or equal to 100 microseconds; when the measurement object is the blood flow rate of a living animal, the exposure time of the camera is greater than or equal to 500 microseconds and less than or equal to 1000 microseconds.

[0042] Exemplarily, according to the Nyquist sampling theorem, when the exposure time is less than 2 times the dynamic speckle decorrelation time (T < 2τc), the error caused by the dynamic speckle time integration can be ignored, and then the dynamic speckle characteristics determined by the blood flow rate can be accurately monitored. That is to say, the optimal exposure time parameter setting depends on the blood flow rate: the smaller the exposure time T, the higher the rate measurement sensitivity, but the less the light flux of the speckle imaging module, which will reduce the signal-to-noise ratio of the speckle image; the larger the exposure time T, due to the dynamic speckle integration effect, the rate measurement sensitivity decreases, and at the same time the light flux of the speckle imaging module increases, which can improve the signal-to-noise ratio of the speckle image; in order to balance the above mutually restrictive factors, for the blood flow rate characteristics of myocardial blood vessels, the optimal exposure time for measuring the blood flow rate of a phantom is 50 μs to 100 μs; the optimal exposure time for measuring the blood flow rate of a living animal is 500 μs to 1000 μs (microseconds). As Figure 5 shown, it is a schematic diagram of the influence of the exposure time on the blood flow rate measurement range in the phantom experiment.

[0043] Specifically, in the above step 201, for the steps of the camera gain optimization strategy, the following step 201d may further be included: Step 201d: Optimize the camera shooting parameters of the imaging unit according to the camera gain optimization strategy.

[0044] Among them, the camera gain optimization strategy includes: when the measurement object is the blood flow rate of a phantom, the camera gain is greater than or equal to 0 dB and less than or equal to 10 dB; when the measurement object is the blood flow rate of a living animal, the camera gain is greater than or equal to 8 dB and less than or equal to 20 dB.

[0045] Exemplarily, to meet the safety standard of the laser irradiation power for biological tissues, the laser illumination uses a relatively low power. At the same time, biological tissues are strong scattering media, resulting in a significant limitation of the received light flux of the imaging system. At this time, the setting of the camera gain parameter becomes particularly crucial. The change in camera gain enhances / weakens both the effective signal and the noise signal simultaneously. Under the condition of constant illumination power, the optimal parameter setting of the camera gain value is related to the ratio of the speckle size to the pixel size and the proportion of the static scattering noise component of the blood flow sample. Therefore, it is necessary to select the optimal camera gain parameter according to the laser speckle hardware system and the blood flow sample. According to the characteristics of the blood flow rate in myocardial blood vessels, the optimal camera gain parameter for measuring the blood flow rate of the phantom is 0 - 10; the optimal camera gain parameter for measuring the blood flow rate of live animals is 8 - 20.

[0046] Exemplarily, after optimizing the system imaging parameters, the acquisition of laser speckle images can be carried out. In the embodiment of the present application, the laser speckle images are acquired through a blood flow rate imaging system, either of the two imaging units. The blood flow rate imaging system further includes: a laser illumination unit; the illumination wavefront generated by the laser illumination unit is: a flat-top beam wavefront; the two imaging units are inclined along the central positions of the two imaging units and the angle with the horizontal direction is less than or equal to 10°.

[0047] Exemplarily, the laser speckle image is quantitatively characterized by the laser speckle contrast K, and its mathematical expression is, K = σI / , where σI is the standard deviation of the intensity of the preprocessed area of the speckle image, that is, the speckle intensity fluctuation; It represents the average intensity of the speckle image preprocessing area. The uniformity of the illumination wavefront is crucial for accurately obtaining the speckle contrast value because the non-uniformity of the illumination wavefront will greatly increase the speckle intensity fluctuation error and even generate incorrect data. Therefore, the optimal wavefront of the laser illumination beam is the flat-top beam wavefront.

[0048] Step 202: Based on the multiple laser speckle images, determine the spatial speckle contrast matrix and the temporal speckle contrast matrix of the observation area, and generate the blood flow index distribution image of the observation area based on the spatial speckle contrast matrix and the temporal speckle contrast matrix.

[0049] Exemplarily, after obtaining the multiple laser speckle images collected, the blood flow index distribution image can be generated through a blood flow rate calculation theoretical model.

[0050] Specifically, the above step 202 may further include the following steps 202a, 202b, and 202c: Step 202a: Obtain the system coherence parameter, and determine the dynamic scattering component proportion coefficient of the observation area according to the system coherence parameter, the spatial speckle contrast matrix, and the temporal speckle contrast matrix.

[0051] Exemplarily, the above system coherence parameter can be obtained through the following steps: Obtain multiple frames of laser speckle images of any area of the static scattering medium within a preset exposure time; Determine the average spatial speckle contrast of the any area according to the multiple frames of laser speckle images; Determine the system coherence parameter based on the following formula (1) according to the average spatial speckle contrast of the area: (Formula (1)) Wherein, is the system coherence parameter, is the spatial speckle contrast.

[0052] Exemplarily, the above step of determining the dynamic scattering component proportion coefficient of the observation area includes: Determine the average spatial speckle contrast according to the spatial speckle contrast matrix; Determine the average temporal speckle contrast according to the temporal speckle contrast matrix; Determine the dynamic scattering component proportion coefficient based on the following formulas (2) to (5) according to the average spatial speckle contrast, the average temporal speckle contrast, and the system coherence parameter: (Formula (2)) (Formula (3)) (Formula (4)) (Formula (5)) Wherein, is the spatial speckle contrast, is the system coherence parameter, is the dynamic scattering component proportion coefficient, x is the blood flow index, and T is the exposure time, is the decoherence time of the scattering medium, is the temporal speckle contrast.

[0053] Step 202b: Determine the blood flow index matrix of the observation area according to the system coherence parameter, the spatial speckle contrast matrix, the temporal speckle contrast matrix, and the dynamic scattering component proportion coefficient.

[0054] Exemplarily, the step of determining the blood flow index matrix of the observation area may include: determining the blood flow index matrix of the observation area according to the system coherence parameter, the spatial speckle contrast matrix, and the dynamic scattering component proportion coefficient based on the above formulas three and four.

[0055] Exemplarily, the step of determining the blood flow index matrix of the observation area may further include: determining the blood flow index matrix of the observation area according to the system coherence parameter, the temporal speckle contrast matrix, and the dynamic scattering component proportion coefficient based on the above formula five.

[0056] Step 202c: Generate a blood flow index distribution image of the observation area according to the blood flow index matrix.

[0057] Exemplarily, taking the myocardial blood flow rate as an example, first, a certain area of the myocardial blood vessels can be selected as the observation area, and multiple frames of laser speckle images of the observation area are acquired. The spatial speckle contrast matrix and the temporal speckle contrast matrix of the multiple frames of laser speckle images can be obtained through data processing. Then, through the spatial speckle contrast matrix, the temporal speckle contrast matrix, and the system coherence parameter, the dynamic scattering component proportion coefficient of the observation area can be obtained through data processing. Then, the blood flow index matrix of the observation area can be obtained through the above data, and the blood flow index distribution image of the observation area can be displayed. In this way, the blood flow index of the observation area can be monitored in real time according to the image.

[0058] Optionally, in the embodiments of the present application, it may be based on, for example, Figure 6 , or for example, Figure 7 shown laser illumination unit for illumination, the laser illumination unit is used to provide illumination to the observation area on the blood vessel surface, and the illumination wavefront generated by the laser illumination unit is: a flat-top beam wavefront.

[0059] For example, as Figure 6 As shown, the laser illumination unit includes: a near-infrared laser, a first mirror, a second mirror, an optical isolator, a fiber optic coupler, an optical fiber, a fiber quasi-diameter, an aspherical lens, and a pyramid prism. As Figure 7 As shown, the laser illumination unit includes: a near-infrared laser, a first mirror, a second mirror, an optical isolator, a fiber optic coupler, an optical fiber, a fiber quasi-diameter, an aspherical lens, and a diffuser.

[0060] Exemplarily, as Figure 8 As shown, any imaging unit included in the above blood flow rate imaging system is composed of an imaging lens, a narrowband filter, an extension sleeve, and a charge-coupled device. The two imaging systems form a camera field of view mosaic in orientations that are tilted to the right and left relative to the vertical direction respectively. The dynamic speckle image received by the camera is a projection image of the myocardial blood flow. To avoid projection errors, the tilt angles of the two groups of cameras relative to the vertical direction are not greater than 10°; to ensure the light flux, the aperture F-number of the imaging lens is not greater than 1.5; the combination of the imaging lens and the extension sleeve changes the magnification of the imaging system to match and form an optimal laser speckle size / pixel size ratio; to conform to the application scenario of large animal myocardial blood vessel imaging and the physical structure compactness of the device, the optimal working distance range of the imaging system is 100 mm - 200 mm (millimeters).

[0061] The large field of view and high dynamic range myocardial blood flow rate imaging method provided by the embodiments of the present application first optimizes the imaging parameters of the imaging unit according to a preset optimization strategy, and uses the optimized imaging unit to collect laser speckle images of the observation area to obtain a plurality of laser speckle images; then, based on the plurality of laser speckle images, a spatial speckle contrast matrix and a temporal speckle contrast matrix of the observation area are determined, and based on the spatial speckle contrast matrix and the temporal speckle contrast matrix, a blood flow index distribution image of the observation area is generated; wherein, the preset optimization strategy includes at least one of the following: a camera imaging field of view size optimization strategy, a speckle image average intensity optimization strategy, an exposure time optimization strategy, and a camera gain optimization strategy. In this way, the signal-to-noise ratio of myocardial blood flow imaging and the measurable range of the blood flow rate can be effectively improved, and the problem of limited myocardial blood flow imaging area can be solved.

[0062] The large field of view and high dynamic myocardial blood flow rate imaging method provided by the embodiments of the present application can visualize the spatio-temporal evolution law of the myocardium in large animals during surgery, improve the quality of coronary artery bypass grafting, and is a key step for laser speckle blood flow imaging equipment to move towards scientific / clinical applications, which puts forward higher requirements for optimizing various parameters of the laser speckle contrast imaging equipment. The large field of view and high dynamic myocardial blood flow rate imaging method provided by the embodiments of the present application comprehensively and systematically verifies the optimal usage parameters by using the laser speckle-blood flow rate theoretical model, simulation experiments and in vivo animal experiments. It can be used to monitor the change in myocardial blood perfusion before and after coronary artery bypass grafting, visualize the spatio-temporal evolution law of the myocardium, and is of great significance for the effective implementation of coronary heart disease surgery and the quantitative evaluation of postoperative effects.

[0063] It should be noted that for the large field of view and high dynamic myocardial blood flow rate imaging method provided by the embodiments of the present application, the execution subject can be a large field of view and high dynamic myocardial blood flow rate imaging device, or a control module in the large field of view and high dynamic myocardial blood flow rate imaging device for executing the large field of view and high dynamic myocardial blood flow rate imaging method. In the embodiments of the present application, taking the large field of view and high dynamic myocardial blood flow rate imaging device executing the large field of view and high dynamic myocardial blood flow rate imaging method as an example, the large field of view and high dynamic myocardial blood flow rate imaging device provided by the embodiments of the present application is described.

[0064] It should be noted that in the embodiments of the present application, the large field of view and high dynamic myocardial blood flow rate imaging methods shown in the above-mentioned various method drawings are all exemplarily described by taking one drawing in the embodiments of the present application as an example. Specifically, when implemented, the large field of view and high dynamic myocardial blood flow rate imaging methods shown in the above-mentioned various method drawings can also be implemented in combination with any other combinable drawings schemed in the above embodiments, which will not be elaborated here.

[0065] The large field of view and high dynamic myocardial blood flow rate imaging device provided by the present application will be described below, and the description below can be mutually referred to the large field of view and high dynamic myocardial blood flow rate imaging method described above.

[0066] Figure 9 is a schematic structural diagram of the large field of view and high dynamic myocardial blood flow rate imaging device provided by the embodiments of the present application, as Figure 9 shown, specifically including: A parameter setting module 901 is configured to optimize the imaging parameters of the imaging unit according to a preset optimization strategy; an image acquisition module 902 is configured to use the optimized imaging unit to acquire laser speckle images of an observation area, obtaining a plurality of laser speckle images; an image generation module 903 is configured to determine a spatial speckle contrast matrix and a temporal speckle contrast matrix of the observation area based on the plurality of laser speckle images, and generate a blood flow index distribution image of the observation area based on the spatial speckle contrast matrix and the temporal speckle contrast matrix; wherein, the preset optimization strategy includes at least one of the following: a camera imaging field of view size optimization strategy, a speckle image average intensity optimization strategy, an exposure time optimization strategy, and a camera gain optimization strategy.

[0067] Optionally, the parameter setting module 901 is specifically configured to optimize the camera shooting parameters of the imaging unit according to the camera imaging field of view size optimization strategy; wherein, the camera imaging field of view size optimization strategy includes: the dark field noise of the camera is less than or equal to 2.5e -1 , the quantum efficiency of the infrared band of the camera is greater than or equal to 30%, the acquisition frame rate range of the camera is: greater than or equal to 60 Hz and less than or equal to 100 Hz, the pixel size of the camera is less than or equal to 3.45 microns, the pixel number range of the camera is: greater than or equal to 1.5 million pixels and less than or equal to 1.6 million pixels, and the magnification range of the imaging lens of the camera is: greater than or equal to 0.3 times and less than or equal to 0.45 times, so that the difference between the ratio of the laser speckle size to the camera pixel size and 1 is minimized.

[0068] Optionally, the parameter setting module 901 is specifically configured to optimize the camera shooting parameters of the imaging unit according to the speckle image average intensity optimization strategy; wherein, the speckle image average intensity optimization strategy includes: the average gray level of the speckle image is greater than or equal to 1 / 4 of the saturation gray level value and less than or equal to 1 / 2 of the saturation gray level value.

[0069] Optionally, the parameter setting module 901 is specifically configured to optimize the camera shooting parameters of the imaging unit according to the exposure time optimization strategy; wherein, the exposure time optimization strategy includes: when the measurement object is the blood flow rate of a phantom, the exposure time of the camera is: greater than or equal to 50 microseconds and less than or equal to 100 microseconds; when the measurement object is the blood flow rate of a live animal, the exposure time of the camera is: greater than or equal to 500 microseconds and less than or equal to 1000 microseconds.

[0070] Optionally, the parameter setting module 901 is specifically configured to optimize the camera shooting parameters of the imaging unit according to the camera gain optimization strategy; wherein, the camera gain optimization strategy includes: when the measurement object is the blood flow rate of a phantom, the camera gain is greater than or equal to 0 dB and less than or equal to 10 dB; when the measurement object is the blood flow rate of a live animal, the camera gain is greater than or equal to 8 dB and less than or equal to 20 dB.

[0071] Optionally, the blood flow rate imaging system further includes: a laser illumination unit; the illumination wavefront generated by the laser illumination unit is: a flat-top beam wavefront; the two imaging units are inclined along the central positions of the two imaging units and the angle with the horizontal direction is less than or equal to 10°.

[0072] Optionally, the image generation module 903 is specifically configured to obtain system coherence parameters, and determine the dynamic scattering component proportion coefficient of the observation area according to the system coherence parameters, the spatial speckle contrast matrix, and the temporal speckle contrast matrix; the image generation module 903 is further specifically configured to determine the blood flow index matrix of the observation area according to the system coherence parameters, the spatial speckle contrast matrix, the temporal speckle contrast matrix, and the dynamic scattering component proportion coefficient; the image generation module 903 is further specifically configured to generate a blood flow index distribution image of the observation area according to the blood flow index matrix.

[0073] The large field of view and high dynamic myocardial blood flow rate imaging device provided by this application first optimizes the imaging parameters of the imaging unit according to a preset optimization strategy, and uses the optimized imaging unit to collect laser speckle images of the observation area to obtain a plurality of laser speckle images; then, based on the plurality of laser speckle images, determine the spatial speckle contrast matrix and the temporal speckle contrast matrix of the observation area, and generate a blood flow index distribution image of the observation area based on the spatial speckle contrast matrix and the temporal speckle contrast matrix; wherein, the preset optimization strategy includes at least one of the following: camera imaging field of view size optimization strategy, speckle image average intensity optimization strategy, exposure time optimization strategy, and camera gain optimization strategy. In this way, the signal-to-noise ratio of myocardial blood flow imaging and the measurable range of blood flow rate can be effectively improved, and the problem of limited myocardial blood flow imaging area can be solved.

[0074] Figure 10 An example of the physical structure diagram of an electronic device is shown in Figure 5 As shown in the figure, the electronic device may include: a processor 1010, a communications interface 1020, a memory 1030, and a communication bus 1040. Among them, the processor 1010, the communications interface 1020, and the memory 1030 communicate with each other via the communication bus 1040. The processor 1010 may call the logic instructions in the memory 1030 to execute the large field of view high dynamic myocardial blood flow rate imaging method, which includes: First, optimize the imaging parameters of the imaging unit according to a preset optimization strategy, and use the optimized imaging unit to collect laser speckle images of the observation area to obtain a plurality of laser speckle images; After that, based on the plurality of laser speckle images, determine the spatial speckle contrast matrix and the temporal speckle contrast matrix of the observation area, and generate the blood flow index distribution image of the observation area based on the spatial speckle contrast matrix and the temporal speckle contrast matrix; Wherein, the preset optimization strategy includes at least one of the following: camera imaging field of view size optimization strategy, speckle image average intensity optimization strategy, exposure time optimization strategy, and camera gain optimization strategy. In this way, the signal-to-noise ratio of myocardial blood flow imaging and the measurable range of blood flow rate can be effectively improved, and the problem of limited myocardial blood flow imaging area can be solved.

[0075] In addition, when the logic instructions in the above-mentioned memory 1030 are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0076] On the other hand, the present application also provides a computer program product. The computer program product includes a computer program stored on a computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute the large field of view and high dynamic myocardial blood flow rate imaging method provided by each of the above methods. The method includes: First, optimize the imaging parameters of the imaging unit according to a preset optimization strategy, and use the optimized imaging unit to collect laser speckle images of the observation area to obtain a plurality of laser speckle images; After that, based on the plurality of laser speckle images, determine the spatial speckle contrast matrix and the temporal speckle contrast matrix of the observation area, and generate a blood flow index distribution image of the observation area based on the spatial speckle contrast matrix and the temporal speckle contrast matrix; Wherein, the preset optimization strategy includes at least one of the following: camera imaging field of view size optimization strategy, speckle image average intensity optimization strategy, exposure time optimization strategy, and camera gain optimization strategy. In this way, the signal-to-noise ratio of myocardial blood flow imaging and the measurable range of blood flow rate can be effectively improved, and the problem of limited myocardial blood flow imaging area can be solved.

[0077] In another aspect, the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it is implemented to execute the large field of view and high dynamic myocardial blood flow rate imaging method provided by each of the above. The method includes: First, optimize the imaging parameters of the imaging unit according to a preset optimization strategy, and use the optimized imaging unit to collect laser speckle images of the observation area to obtain a plurality of laser speckle images; After that, based on the plurality of laser speckle images, determine the spatial speckle contrast matrix and the temporal speckle contrast matrix of the observation area, and generate a blood flow index distribution image of the observation area based on the spatial speckle contrast matrix and the temporal speckle contrast matrix; Wherein, the preset optimization strategy includes at least one of the following: camera imaging field of view size optimization strategy, speckle image average intensity optimization strategy, exposure time optimization strategy, and camera gain optimization strategy. In this way, the signal-to-noise ratio of myocardial blood flow imaging and the measurable range of blood flow rate can be effectively improved, and the problem of limited myocardial blood flow imaging area can be solved.

[0078] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative effort.

[0079] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the above technical solution, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present application.

Claims

1. A large field of view and high dynamic myocardial blood flow rate imaging method, characterized in that, Any one of the two imaging units applied in the blood flow rate imaging system; The method includes: Optimizing the imaging parameters of the imaging unit according to a preset optimization strategy, and using the optimized imaging unit to collect laser speckle images of the observation area to obtain a plurality of laser speckle images; Based on the plurality of laser speckle images, determining the spatial speckle contrast matrix and the temporal speckle contrast matrix of the observation area, and generating a blood flow index distribution image of the observation area based on the spatial speckle contrast matrix and the temporal speckle contrast matrix; Wherein, the preset optimization strategy includes at least one of the following: camera imaging field of view size optimization strategy, speckle image average intensity optimization strategy, exposure time optimization strategy, and camera gain optimization strategy.

2. The method according to claim 1, characterized in that The optimizing the imaging parameters of the imaging unit according to a preset optimization strategy includes: Optimizing the camera shooting parameters of the imaging unit according to the camera imaging field of view size optimization strategy; Among them, the optimization strategy for the camera imaging field-of-view size includes: the dark-field noise of the camera is less than or equal to 2.5e -1 , the quantum efficiency of the infrared band of the camera is greater than or equal to 30%, the acquisition frame rate range of the camera is: greater than or equal to 60 Hz and less than or equal to 100 Hz, the pixel size of the camera is less than or equal to 3.45 microns, the pixel number range of the camera is: greater than or equal to 1.5 million pixels and less than or equal to 1.6 million pixels, and the magnification range of the imaging lens of the camera is: greater than or equal to 0.3 times and less than or equal to 0.45 times, so that the difference between the ratio of the laser speckle size to the camera pixel size and 1 is minimized.

3. The method according to claim 1, wherein The optimizing the imaging parameters of the imaging unit according to a preset optimization strategy includes: Optimizing the camera shooting parameters of the imaging unit according to the speckle image average intensity optimization strategy; Wherein, the speckle image average intensity optimization strategy includes: the average gray level of the speckle image is greater than or equal to 1 / 4 of the saturation gray level value and less than or equal to 1 / 2 of the saturation gray level value.

4. The method according to claim 1, characterized in that, The optimizing the imaging parameters of the imaging unit according to a preset optimization strategy includes: Optimizing the camera shooting parameters of the imaging unit according to the exposure time optimization strategy; Wherein, the exposure time optimization strategy includes: when the measurement object is the blood flow rate of a phantom, the exposure time of the camera is greater than or equal to 50 microseconds and less than or equal to 100 microseconds; when the measurement object is the blood flow rate of a live animal, the exposure time of the camera is greater than or equal to 500 microseconds and less than or equal to 1000 microseconds.

5. The method according to claim 1, wherein The optimizing the imaging parameters of the imaging unit according to a preset optimization strategy includes: Optimizing the camera shooting parameters of the imaging unit according to the camera gain optimization strategy; Wherein, the camera gain optimization strategy includes: when the measurement object is the blood flow rate of a phantom, the camera gain is greater than or equal to 0 dB and less than or equal to 10 dB; when the measurement object is the blood flow rate of a live animal, the camera gain is greater than or equal to 8 dB and less than or equal to 20 dB.

6. The method according to any one of claims 1 to 5, characterized in that The blood flow rate imaging system further includes: a laser illumination unit; the illumination wavefront generated by the laser illumination unit is: a flat-top beam wavefront; the two imaging units are inclined along the central positions of the two imaging units and the angle with the horizontal direction is less than or equal to 10°.

7. The method according to claim 6, wherein The determining the spatial speckle contrast matrix and the temporal speckle contrast matrix of the observation area based on the plurality of laser speckle images, and generating a blood flow index distribution image of the observation area based on the spatial speckle contrast matrix and the temporal speckle contrast matrix includes: Obtain system coherence parameters, and determine the dynamic scattering component proportion coefficient of the observation area according to the system coherence parameters, the spatial speckle contrast matrix, and the temporal speckle contrast matrix; Determine the blood flow index matrix of the observation area according to the system coherence parameters, the spatial speckle contrast matrix, the temporal speckle contrast matrix, and the dynamic scattering component proportion coefficient; Generate a blood flow index distribution image of the observation area according to the blood flow index matrix; 8. A large field of view and high dynamic range myocardial blood flow velocity imaging device, characterized in that, Applied to any one of the two imaging units in the blood flow rate imaging system; The device includes: A parameter setting module for optimizing the imaging parameters of the imaging unit according to a preset optimization strategy; An image acquisition module for using the optimized imaging unit to acquire laser speckle images of the observation area to obtain a plurality of laser speckle images; An image generation module for determining the spatial speckle contrast matrix and the temporal speckle contrast matrix of the observation area based on the plurality of laser speckle images, and generating a blood flow index distribution image of the observation area based on the spatial speckle contrast matrix and the temporal speckle contrast matrix; Wherein, the preset optimization strategy includes at least one of the following: a camera imaging field of view size optimization strategy, a speckle image average intensity optimization strategy, an exposure time optimization strategy, and a camera gain optimization strategy.

9. An electronic device, characterized in that, Including a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the program, the steps of the large field of view and high dynamic myocardial blood flow rate imaging method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that, A computer program is stored thereon, and when the computer program is executed by a processor, the steps of the large field of view and high dynamic myocardial blood flow rate imaging method according to any one of claims 1 to 7 are implemented.

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