Blood flow acquisition method, device, equipment and blood flow reserve fraction acquisition method

Abstract

The present application provides a blood flow acquisition method, device, equipment and blood flow reserve fraction acquisition method. The blood flow acquisition method provided by the present application includes: acquiring multiple spectral signals at a preset position of the blood vessel segment to be measured within a preset time length; starting from the second spectral signal, traversing the multiple spectral signals in sequence; for any position within the scanning range, determining the phase difference between the currently traversed target spectral signal and the previous spectral signal at the position, and obtaining the phase difference of the target spectral signal corresponding to the position; calculating the blood flow corresponding to the target spectral signal according to the wavelength of the light source, the sampling frame rate, the angle between the light emitting direction and the blood flow direction, the flushing agent flow rate, and all the phase differences of the target spectral signal corresponding to all positions within the scanning range; calculating the blood flow of the blood vessel segment to be measured according to the blood flow corresponding to all the target spectral signals. The method provided by the present application can accurately obtain blood flow and blood flow reserve fraction.

Description

Technical Field

[0001] The present application relates to the technical field of medical image data processing, and in particular to a blood flow acquisition method, device, equipment and blood flow reserve fraction acquisition method. Background Art

[0002] Fractional Flow Reserve (FFR) refers to the ratio of the maximum blood flow that can be obtained in the myocardial area supplied by the blood vessels to the maximum blood flow that can be obtained in the same area under normal conditions in theory when there is a stenotic lesion in the coronary artery, that is, the ratio of the mean pressure in the stenotic distal coronary artery to the mean pressure in the aorta at the coronary artery orifice under the state of maximum myocardial hyperemia. A large number of scientific studies and clinical trials have shown that FFR can accurately evaluate the severity of myocardial ischemia in patients. In clinical practice, it is used as a functional evaluation indicator to guide whether coronary intervention is needed and to conduct postoperative evaluation.

[0003] In recent years, methods based on fluid mechanics simulation models or dimensionality reduction fluid mechanics models can be used to calculate FFR based on medical images. The above methods all use the patient's blood flow as a calculation prerequisite, and how to accurately obtain the patient's blood flow has become a hot topic in current research. Summary of the invention

[0004] In view of this, the present application provides a blood flow acquisition method, device, equipment and blood flow reserve fraction acquisition method, which are used to accurately acquire the patient's blood flow, and then accurately acquire the patient's blood flow reserve fraction.

[0005] Specifically, the present application is implemented through the following technical solutions:

[0006] In a first aspect, the present application provides a method for obtaining blood flow, the method comprising:

[0007] Acquire multiple spectral signals obtained by OCT scanning at a preset position of the blood vessel segment to be measured within a preset time period;

[0008] Starting from the second spectral signal of the multiple spectral signals, the multiple spectral signals are traversed in sequence; for any position within the scanning range of the OCT scan, a phase difference between the currently traversed target spectral signal and the previous spectral signal at the position is determined to obtain the phase difference of the target spectral signal corresponding to the position;

[0009] The blood flow corresponding to the target spectral signal is calculated by using the predetermined functional relationship between the blood flow, the flushing agent flow and the phase difference, according to the wavelength of the light source of the OCT system, the sampling frame rate, the angle between the light emitting direction and the blood flow direction, the flushing agent flow, and all the phase differences of the target spectral signal corresponding to all the positions within the scanning range; wherein the predetermined functional relationship between the blood flow, the flushing agent flow and the phase difference is jointly determined by a first functional relationship between the fluid flow and the fluid flow velocity at any position within the scanning range, a second functional relationship between the fluid flow velocity at any position within the scanning range and the phase difference and the refractive index of the mixed fluid after the blood and the flushing agent are mixed, a third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed, the fluid flow, the flushing agent flow, and the functional relationship between the fluid flow, the flushing agent flow and the blood flow; the third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed, the fluid flow, and the flushing agent flow is determined according to the Lorentz equation;

[0010] The blood flow rate of the blood vessel segment to be measured is calculated according to the blood flow rates corresponding to all target spectral signals.

[0011] A second aspect of the present application provides a method for obtaining a blood flow reserve fraction, the method comprising:

[0012] Acquire an OCT image sequence of the target blood vessel segment;

[0013] Performing vascular lumen segmentation and branch detection on the OCT image sequence respectively to obtain a segmentation result and a branch detection result;

[0014] Determining the preset position of each branch blood vessel segment in the target blood vessel segment according to the branch detection result;

[0015] For each branch blood vessel segment, using any of the methods provided in the first aspect of the present application to obtain the blood flow of the branch blood vessel segment;

[0016] The blood flow reserve fraction is determined according to the blood flow of each branch vessel segment and the segmentation result.

[0017] A second aspect of the present application provides a blood flow acquisition device, the device comprising the acquisition module, the processing module, the determination module and the calculation module; wherein;

[0018] The acquisition module is used to acquire a plurality of spectral signals obtained by OCT scanning at a preset position of the blood vessel segment to be measured within a preset time period;

[0019] The processing module is used to traverse the multiple spectral signals in sequence starting from the second spectral signal of the multiple spectral signals;

[0020] The determination module is used to determine the phase difference between the current target spectrum signal and the previous spectrum signal at any position within the scanning range of the OCT scan, and obtain the phase difference of the target spectrum signal corresponding to the position;

[0021] The determination module is used to calculate the blood flow corresponding to the target spectral signal by using the predetermined functional relationship between the blood flow, the flushing agent flow and the phase difference, according to the light source wavelength, sampling frame rate, angle between the light emitting direction and the blood flow direction, flushing agent flow, and all phase differences of the target spectral signal corresponding to all positions within the scanning range of the OCT system; wherein the predetermined functional relationship between the blood flow, the flushing agent flow and the phase difference is determined by a first functional relationship between the fluid flow and the fluid flow velocity at any position within the scanning range, a second functional relationship between the fluid flow velocity at any position within the scanning range and the phase difference and the refractive index of the mixed fluid after the blood and the flushing agent are mixed, a third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed, the fluid flow, the flushing agent flow, and the functional relationship between the fluid flow, the flushing agent flow and the blood flow; the third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed, the fluid flow, and the flushing agent flow is determined according to the Lorentz equation;

[0022] The calculation module is used to calculate the blood flow of the blood vessel segment to be measured according to the blood flow corresponding to all target spectral signals.

[0023] The third aspect of the present application provides a blood flow acquisition device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of any one of the methods provided in the first aspect of the present application are implemented.

[0024] The fourth aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any one of the methods provided in the first aspect of the present application.

[0025] The blood flow acquisition method, device, equipment and blood flow reserve fraction acquisition method provided in the present application can determine the functional relationship between the blood flow, the flushing agent flow and the phase difference by determining the third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed according to the Lorentz-Lorentz equation, and then combining the first functional relationship between the fluid flow and the fluid flow velocity at any position in the scanning range, the second functional relationship between the fluid flow velocity at any position in the scanning range and the phase difference and the refractive index of the mixed fluid after the blood and the flushing agent are mixed, and the functional relationship between the fluid flow, the flushing agent flow and the blood flow, so as to further obtain multiple spectral signals obtained by OCT scanning at a preset position of the blood vessel segment to be measured within a preset time length, and from Starting from the second spectral signal of the multiple spectral signals, the multiple spectral signals are traversed in sequence, and then for any position within the scanning range of the OCT scan, the phase difference between the currently traversed target spectral signal and the previous spectral signal at the position is determined to obtain the phase difference of the target spectral signal corresponding to the position. In this way, the blood flow corresponding to the target spectral signal can be calculated based on the functional relationship between the blood flow, the flushing agent flow and the phase difference, the light source wavelength of the OCT system, the sampling frame rate, the angle between the light emitting direction and the blood flow direction, the flushing agent flow, and all the phase differences of the target spectral signal corresponding to all positions within the scanning range, and then the blood flow of the blood vessel segment to be measured is calculated based on the blood flow corresponding to all target spectral signals. In this way, by introducing the refractive index of the mixed fluid after mixing blood and the flushing agent, and then using the refractive index of the mixed fluid after mixing blood and the flushing agent to correct the blood flow, the calculation accuracy of the blood flow can be improved, so that the calculated blood flow is close to the actual flow. In this way, the accuracy of the calculated blood flow can be improved. In addition, when calculating the blood flow of the blood vessel segment to be measured, the calculation is based on multiple target spectral signals within a preset time length, which can avoid the influence of the cardiac cycle on the calculation result, and can further improve the accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of Embodiment 1 of the blood flow acquisition method provided in this application;

[0027] Figure 2 A schematic diagram of a scanning range of an OCT scan according to an exemplary embodiment of the present application;

[0028] Figure 3 This is a schematic diagram of the angle between the light emitting direction and the blood flow direction shown in an exemplary embodiment of the present application;

[0029] Figure 4 A flow chart showing a functional relationship between blood flow rate, flushing agent flow rate and phase difference according to an exemplary embodiment of the present application;

[0030] Figure 5 This is a flow chart of Embodiment 3 of the method for obtaining the blood flow reserve fraction provided in the present application;

[0031] Figure 6 This is a schematic diagram showing an implementation principle of determining a preset position according to an exemplary embodiment of the present application;

[0032] Figure 7 A hardware structure diagram of a blood flow acquisition device in which the blood flow acquisition device provided in this application is located;

[0033] Figure 8 This is a structural schematic diagram of embodiment 1 of the blood flow acquisition device provided in this application. DETAILED DESCRIPTION

[0034] Here, exemplary embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application.

[0035] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used in this article refers to and includes any or all possible combinations of one or more associated listed items.

[0036] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0037] Specific embodiments are given below to introduce the technical solution of the present application in detail.

[0038] Figure 1 This is a flow chart of the first embodiment of the blood flow acquisition method provided by this application. Please refer to Figure 1 , the method provided in this embodiment may include:

[0039] S101 , obtaining a plurality of spectral signals obtained by OCT scanning at a preset position of a blood vessel segment to be measured within a preset time period.

[0040] Specifically, the blood vessel segment to be measured is set according to actual needs, and is not limited in this embodiment. For example, in a possible implementation, the diseased blood vessel segment is determined as the blood vessel segment to be measured. Further, the preset position is also set according to actual needs, and is not limited in this embodiment. For example, in a possible implementation, the preset position of the blood vessel segment to be measured can be any position inside the blood vessel segment to be measured, and the following description is taken as an example that the preset position is the middle position of the blood vessel segment to be measured.

[0041] Furthermore, the preset duration is set according to actual needs, and is not limited in this embodiment. For example, in a possible implementation, the preset duration can be set according to the cardiac cycle, and the preset duration is equal to at least one cardiac cycle. That is, the preset duration is equal to an integer multiple of the patient's cardiac cycle. For example, in one embodiment, the preset duration is equal to 1 cardiac cycle; for another example, in another embodiment, the preset duration is equal to 2 cardiac cycles.

[0042] It should be noted that, in specific implementation, the cardiac cycle can be calibrated by X-ray angiography or electrocardiogram to accurately obtain the cardiac cycle.

[0043] In specific implementation, after the blood vessel segment to be measured, the preset position, and the preset time are set, multiple spectral signals obtained by OCT scanning at the preset position of the blood vessel segment to be measured within the preset time can be obtained. The specific acquisition method is as follows:

[0044] (1) The OCT probe is inserted into the preset position of the blood vessel segment to be measured through the catheter.

[0045] (2) Inject a flushing agent (in this embodiment, the flushing agent may be saline) into the blood vessel segment to be tested to reduce the blood concentration.

[0046] (3) Starting the OCT probe to rotate in situ to obtain multiple spectral signals at the preset position.

[0047] It should be noted that in the process of using OCT scanning to obtain spectral signals, due to the scattering and absorption of light by blood, OCT scanning cannot directly penetrate the blood flow to observe the blood vessel wall or areas relatively far away from the OCT probe. Therefore, before OCT scanning, flushing agent needs to be injected into the blood vessel segment to be tested to reduce the blood concentration, thereby improving the visibility of the OCT scan.

[0048] In specific implementation, after the OCT probe reaches the preset area of ​​the blood vessel segment to be measured, the OCT probe is started to rotate in situ to adjust the flushing agent flow rate. (For the convenience of explanation, the flushing agent flow rate is recorded as ) The flushing agent is injected at a uniform speed. Further, when the complete vascular wall structure can be observed in the OCT image, the OCT probe is controlled to continue scanning in situ and collect data for a preset time period from this moment to obtain multiple spectral signals.

[0049] It should be noted that one spectral signal represents a spectral signal obtained when the probe rotates one circle.

[0050] S102 , starting from the second spectral signal of the plurality of spectral signals, traverse the plurality of spectral signals in sequence.

[0051] For example, in a possible implementation, N spectral signals are obtained, and for the convenience of description, these N spectral signals are respectively recorded as spectral signal 1, spectral signal 2, spectral signal 3, ..., spectral signal N. In this step, starting from spectral signal 2, these N spectral signals are traversed in sequence.

[0052] S103 . For any position within the scanning range of the OCT scan, determine the phase difference between the currently traversed target spectrum signal and the previous spectrum signal at the position, and obtain the phase difference of the target spectrum signal corresponding to the position.

[0053] It should be noted that Figure 2 This is a schematic diagram of the scanning range of OCT scanning shown in an exemplary embodiment of the present application. Figure 2 , the scanning range of OCT scanning refers to the scanning range in the polar coordinate system, which is a sector-shaped area covering the entire circumference and radial depth, which can be represented by the angle range and radial distance in polar coordinates. Further, for the convenience of explanation, the angle range in polar coordinates is represented by θ, and the radial distance in polar coordinates is represented by ρ, where the scanning range refers to the area indicated by θ from 0° to 360° and ρ from 0 to R (where R is the detection depth of the OCT scan).

[0054] In this step, for any position (θ, ρ) in the scanning range, the phase difference between the current target spectrum signal and the previous spectrum signal at the position can be determined to obtain the phase difference of the target spectrum signal corresponding to the position. For example, for the position (0°, R) in the scanning range, the phase difference between spectrum signal 2 and spectrum signal 1 at the position can be determined, and then the phase difference is determined as the phase difference of spectrum signal 2 corresponding to the position (0°, R). For another example, for the position (360°, 0) in the scanning range, the phase difference between spectrum signal 2 and spectrum signal 1 at the position can be determined, and then the phase difference is determined as the phase difference of spectrum signal 2 corresponding to the position (360°, 0).

[0055] Further, referring to the previous introduction, in this step, for example, for the position (0°, R), the phase difference of spectral signal 2 corresponding to the position (0°, R) can be obtained based on spectral signal 2 and spectral signal 1; the phase difference of spectral signal 3 corresponding to the position (0°, R) can be obtained based on spectral signal 3 and spectral signal 2; ...; similarly, the phase difference of spectral signal N corresponding to the position (0°, R) can be obtained based on spectral signal N and spectral signal N-1. That is, corresponding to a certain position, the phase differences of N-1 spectral signals corresponding to the position can be obtained.

[0056] Furthermore, for a certain target spectral signal (any spectral signal after the first spectral signal is the target spectral signal), the phase difference of the spectral signal corresponding to any position in the scanning range can be obtained. For example, for spectral signal 2, the phase difference of the spectral signal corresponding to any position in the scanning range can be obtained.

[0057] S104. Calculate the blood flow corresponding to the target spectral signal by using a predetermined functional relationship among blood flow, flushing agent flow and phase difference, according to the light source wavelength, sampling frame rate, angle between the light emitting direction and the blood flow direction, flushing agent flow, and all phase differences of the target spectral signal corresponding to all positions within the scanning range of the OCT system.

[0058] It should be noted that the predetermined functional relationship between the blood flow rate, the flushing agent flow rate and the phase difference is jointly determined by a first functional relationship between the fluid flow rate and the fluid flow velocity at any position within the scanning range, a second functional relationship between the fluid flow velocity at any position within the scanning range and the phase difference and the refractive index of the mixed fluid after the blood and the flushing agent are mixed, a third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed and the fluid flow rate, the flushing agent flow rate, and the functional relationship between the fluid flow rate, the flushing agent flow rate and the blood flow rate; the third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed and the fluid flow rate, the flushing agent flow rate is determined according to the Lorentz equation.

[0059] Specifically, according to the Doppler frequency shift, the fluid flow rate can be calculated according to the phase difference corresponding to a certain position. The second functional relationship between the fluid flow rate at any position within the scanning range and the phase difference and the refractive index of the mixed fluid after the blood and the flushing agent are mixed is as follows:

[0060] ;

[0061] in, For location The fluid flow rate; is the phase difference corresponding to this position; is the wavelength of the light source of the OCT system; is the acquisition frame rate of the OCT system, is the refractive index of the mixed fluid after the blood and the flushing agent are mixed; It is the angle between the light emitting direction of the OCT probe and the blood flow direction.

[0062] Figure 3 This is a schematic diagram of the angle between the light emitting direction and the blood flow direction according to an exemplary embodiment of the present application. Figure 3 Based on the above embodiments, it can be understood that the fluid flow rate (the flow rate of the mixed fluid after the blood and the flushing agent are mixed) through the cross section of the preset position can be expressed as:

[0063] ;

[0064] in, is the fluid flow rate; For location The fluid velocity, see Figure 2 ,Location Refers to the area to the right of the center of the image, clockwise Angle, distance from center The location of the place.

[0065] Referring to the above description, it can be understood that the first functional relationship between the fluid flow rate and the fluid flow velocity at any position within the scanning range is as shown in the above formula (2).

[0066] The following is an introduction to the method for determining the functional relationship between the predetermined blood flow rate, the flushing agent flow rate and the phase difference. Specifically, Figure 4 This is a flow chart showing the functional relationship between blood flow, flushing agent flow and phase difference according to an exemplary embodiment of the present application. Please refer to Figure 4 In a possible implementation, the method for determining the predetermined functional relationship between the blood flow rate, the flushing agent flow rate and the phase difference includes:

[0067] S401. Determine the third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed and the fluid flow rate and the flushing agent flow rate according to the Lorentz-Lorentz equation; wherein the constant term in the third functional relationship is related to the refractive index of the blood, the refractive index of the flushing agent, the molar volume of the blood and the molar volume of the flushing agent.

[0068] In specific implementation, the implementation process of this step may include:

[0069] (1) According to the molar volume of blood and the molar volume of flushing agent, a fourth functional relationship between the molar fraction of blood and the flushing agent flow rate and the fluid flow rate, and a fifth functional relationship between the molar fraction of flushing agent and the flushing agent flow rate and the fluid flow rate are determined respectively.

[0070] Specifically, it can be understood that the molar fraction of blood satisfies the following relationship:

[0071] ;

[0072] in, is the molar fraction of blood, is the amount of substance in blood, The amount of the substance of the flushing agent, For blood flow, is the flow rate of flushing agent, are the molar volume of blood and the molar volume of flushing agent.

[0073] It is understandable that fluid flow Equal to the blood flow and flushing agent flow The sum of the mole fraction of blood and the flow rate of flushing agent is equal to the difference between the flow rate of fluid and the flow rate of flushing agent. Therefore, based on formula (3), the fourth functional relationship between the mole fraction of blood and the flow rate of flushing agent and the flow rate of fluid can be obtained. The fourth functional relationship can be expressed as:

[0074] ;

[0075] Similarly, the mole fraction of the flushing agent satisfies the following relationship:

[0076] ;

[0077] in, is the mole fraction of the flushing agent, and Respectively represent the flow rate of blood and the flow rate of flushing agent, and represent the molar volume of blood and the molar volume of flushing agent respectively.

[0078] Referring to the previous description, the blood flow rate is equal to the difference between the fluid flow rate and the flushing agent flow rate. Therefore, based on formula (5), the fifth functional relationship between the mole fraction of the flushing agent and the flushing agent flow rate and the fluid flow rate can be obtained. The fifth functional relationship can be expressed as:

[0079] .

[0080] It should be noted that the molar volume of blood and the molar volume of flushing agent can be obtained in vitro. Therefore, referring to formula (4) and formula (6), the molar fraction of blood is directly related to the flushing agent flow rate and the fluid flow rate, which can be expressed as a functional relationship between the flushing agent flow rate and the fluid flow rate, as shown in formula (4); similarly, the molar fraction of flushing agent is also directly related to the flushing agent flow rate and the fluid flow rate, which can be expressed as a functional relationship between the flushing agent flow rate and the fluid flow rate, as shown in formula (6).

[0081] It should be noted that, in specific implementation, the molar volume of blood and the molar volume of flushing agent can be calculated according to the following formula:

[0082] ;

[0083] Wherein, V is the volume of the liquid, m is the mass of the liquid, and M is the relative molecular mass of the liquid. It should be explained that the relative molecular mass can be measured by an instrument. Further, for flushing agents, different flushing agents have different relative molecular masses.

[0084] (2) Substituting the fourth functional relationship and the fifth functional relationship into the Lorentz equation, the third functional relationship formula between the refractive index of the mixed fluid after the blood and the flushing agent are mixed and the fluid flow rate and the flushing agent flow rate is obtained.

[0085] Specifically, the mathematical expression of the Lorentz equation is as follows:

[0086] ;

[0087] in, is the refractive index of the mixed fluid after mixing blood and flushing agent, and are the mole fractions of blood and flushing agent, respectively, and are the refractive indices of blood and flushing agent, respectively.

[0088] In this step, the fourth functional relationship and the fifth functional relationship are substituted into the Lorentz equation to obtain the third functional relationship formula between the refractive index of the mixed fluid after the blood and the flushing agent are mixed and the fluid flow rate and the flushing agent flow rate. The third functional relationship formula is shown as follows:

[0089] ;

[0090] in, is the refractive index of the mixed fluid after mixing blood and flushing agent, and are the refractive indices of blood and flushing agent, respectively. is the fluid flow rate, is the flushing agent flow rate, and represent the molar volume of blood and the molar volume of flushing agent respectively.

[0091] Please continue to refer to formula (9). It can be understood that in the above formula, the refractive index of blood, the refractive index of flushing agent, the molar volume of blood, and the molar volume of flushing agent are fixed quantities. Therefore, it can be seen that the refractive index of the mixed fluid after the blood and flushing agent are mixed is only related to the fluid flow rate and the flushing agent flow rate. The refractive index of the mixed fluid can be expressed as a function of the fluid flow rate and the flushing agent flow rate. The functional relationship is obtained by deforming formula (9), and the constant term in the functional relationship is related to the refractive index of blood, the refractive index of flushing agent, the molar volume of blood, and the molar volume of flushing agent.

[0092] S402: Substitute the third functional relationship into the second functional relationship between the fluid flow rate and the phase difference at any position within the scanning range and the refractive index of the mixed fluid after the blood and the flushing agent are mixed, to obtain an intermediate functional relationship.

[0093] Specifically, the third functional relationship represents the relationship between the refractive index of the mixed fluid and the fluid flow rate and the flushing agent flow rate. Further, the refractive index of the mixed fluid can be represented by the fluid flow rate and the flushing agent flow rate. , further, Substituting it into formula (1), we can get the intermediate function relationship.

[0094] Specifically, the intermediate function relationship is relatively complex, and its specific form is not described in this embodiment. It can be understood that through the intermediate function, it can be known that the fluid flow rate is related to the refractive index of blood, the refractive index of flushing agent, the molar volume of blood, the molar volume of flushing agent, the fluid flow rate, the flushing agent flow rate, and the wavelength of the light source, the sampling frequency, the angle between the light output direction and the blood flow direction, and the phase difference; wherein, relative to a surgical operation of the same patient, the refractive index of blood, the refractive index of flushing agent, the molar volume of blood, and the molar volume of flushing agent are fixed quantities, and further, relative to the same OCT device and the same catheter, the wavelength of the light source, the sampling frequency, the angle between the light output direction and the blood flow direction are also fixed quantities, therefore, the fluid flow rate can be expressed as a functional relationship between the fluid flow rate, the flushing agent flow rate and the phase difference, that is, the implicit representation of the intermediate function can be:

[0095] ;

[0096] in, For location The fluid flow rate, is the fluid flow rate, is the flushing agent flow rate, For the corresponding position The phase difference.

[0097] S403. Determine the functional relationship between the blood flow, the flushing agent flow and the phase difference based on the intermediate functional relationship, the first functional relationship between the fluid flow and the fluid flow rate at any position within the scanning range, and the functional relationship between the fluid flow, the flushing agent flow and the blood flow.

[0098] In specific implementation, the intermediate function is substituted into formula (2) to obtain the functional relationship between the fluid flow rate, the flushing agent flow rate and the phase difference:

[0099] .

[0100] From the above formula, we can know that the fluid flow rate is related to and Furthermore, based on the functional relationship between the fluid flow rate, the flushing agent flow rate and the blood flow rate, it can be seen that the fluid flow rate is equal to the sum of the blood flow rate and the flushing agent flow rate. Therefore, the blood flow rate can be expressed as the functional relationship between the flushing agent flow rate and the phase difference. The implicit expression of the functional relationship between the blood flow rate, the flushing agent flow rate and the phase difference can be:

[0101] ;

[0102] in, For blood flow, For the corresponding position Phase difference; is the flushing agent flow rate. The value of is from 0° to 360°. The value of is from 0 to R.

[0103] Referring to the previous description, it can be understood that the blood flow is related to the wavelength of the light source, the sampling frame rate, the angle between the light output direction and the blood flow direction, the flushing agent flow rate, and all phase differences of the spectral signal corresponding to all positions within the scanning range. In this step, the above quantities are substituted into the functional relationship between the blood flow, the flushing agent flow rate and the phase difference to calculate the blood flow corresponding to the spectral signal.

[0104] For example, for spectral signal 2, the wavelength of the light source, the sampling frame rate, the angle between the light output direction and the blood flow direction, the flushing agent flow rate, and all phase differences of spectral signal 2 corresponding to all positions within the scanning range are substituted into the functional relationship to obtain the blood flow corresponding to spectral signal 2.

[0105] Similarly, through the above method, the blood flow corresponding to any spectral signal after spectral signal 1 can be obtained.

[0106] S105 , calculating the blood flow of the blood vessel segment to be measured according to the blood flow corresponding to all target spectral signals.

[0107] Specifically, due to the influence of cardiac contraction and relaxation, the blood flow of the same blood vessel segment to be measured is not fixed at different periods in a cardiac cycle. Therefore, in this embodiment, the blood flow of the blood vessel segment to be measured in a cardiac cycle can be calculated based on the blood flow corresponding to all target spectral signals.

[0108] In a specific implementation, in a possible implementation manner, the average value of the blood flow corresponding to all current spectral signals may be calculated, and then the average value may be determined as the blood flow of the blood vessel segment to be measured.

[0109] The method provided in this embodiment determines the third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed and the fluid flow rate and the flushing agent flow rate according to the Lorentz-Lorentz equation, and then combines the first functional relationship between the fluid flow rate and the fluid flow velocity at any position in the scanning range, the second functional relationship between the fluid flow velocity at any position in the scanning range and the phase difference and the refractive index of the mixed fluid after the blood and the flushing agent are mixed, and the functional relationship between the fluid flow rate, the flushing agent flow rate and the blood flow rate, so as to determine the functional relationship between the blood flow rate, the flushing agent flow rate and the phase difference.

[0110] The method provided in this embodiment obtains multiple spectral signals obtained by OCT scanning at a preset position of the blood vessel segment to be measured within a preset time period, and starts from the second spectral signal of the multiple spectral signals, sequentially traverses the multiple spectral signals, and then for any position within the scanning range of the OCT scan, determines the phase difference between the current traversed target spectral signal and the previous spectral signal at the position, and obtains the phase difference of the target spectral signal corresponding to the position. In this way, the blood flow corresponding to the target spectral signal can be calculated based on the functional relationship between the blood flow, the flushing agent flow and the phase difference, the light source wavelength of the OCT system, the sampling frame rate, the angle between the light output direction and the blood flow direction, the flushing agent flow, and all the phase differences of the target spectral signal corresponding to all positions within the scanning range, and then the blood flow of the blood vessel segment to be measured is calculated based on the blood flow corresponding to all the target spectral signals. In this way, by introducing the refractive index of the mixed fluid after mixing blood and the flushing agent, and then using the refractive index of the mixed fluid after mixing blood and the flushing agent to correct the blood flow, the calculation accuracy of the blood flow can be improved, so that the calculated blood flow is close to the actual flow. In this way, the accuracy of the calculated blood flow can be improved. In addition, when calculating the blood flow of the blood vessel segment to be measured, the calculation is based on multiple target spectral signals within a preset time length, which can avoid the influence of the cardiac cycle on the calculation result, and can further improve the accuracy.

[0111] Furthermore, the present application also provides a method for obtaining a blood flow reserve fraction. The method for obtaining a blood flow reserve fraction provided by the present application is introduced below:

[0112] Figure 5 This is a flow chart of Example 1 of the method for obtaining the blood flow reserve fraction provided in this application. Please refer to Figure 5 , the method provided in this embodiment may include:

[0113] S501 : Acquire an OCT image sequence of a target blood vessel segment.

[0114] Specifically, the target blood vessel segment is set according to actual needs, and is not limited in this embodiment. For example, in a possible implementation, the blood vessel segment to be tested during actual patient testing is the target blood vessel segment.

[0115] In specific implementation, the OCT probe can be sent to the distal end of the target blood vessel segment, and contrast agent can be injected into the blood vessel until the blood is completely flushed out. When there is no obvious blood flow signal in the OCT probe, the OCT probe will automatically rotate back to obtain an OCT image sequence of the target blood vessel segment.

[0116] S502 , performing blood vessel lumen segmentation and branch detection on the OCT image sequence respectively to obtain a segmentation result and a branch detection result.

[0117] Blood vessel lumen segmentation refers to separating the inner region of the blood vessel lumen in the OCT image to obtain the contour information of the blood vessel. Furthermore, branch detection refers to detecting the bifurcation points and branch vessel segments of the blood vessel in the OCT image.

[0118] Specifically, the branch detection result is usually a set of coordinate points, which represent the position of the bifurcation point in the blood vessel, and the starting position and the ending position of the branch blood vessel segment associated with each bifurcation point.

[0119] Specifically, the specific implementation principles and processes of vascular lumen segmentation and branch detection can be found in the introduction of related technologies, which will not be repeated here.

[0120] S503: Determine a preset position of each branch blood vessel segment in the target blood vessel segment according to the branch detection result.

[0121] Specifically, in a possible implementation, the front part, the middle part or the tail part of the branch blood vessel segment may be selected as the preset position, which is not limited in this embodiment. Figure 6 This is a schematic diagram showing the implementation principle of determining a preset position according to an exemplary embodiment of the present application. Figure 6 ,exist Figure 6 In the example shown, the middle of the branch vessel segment is selected as the preset position.

[0122] It should be noted that, in a possible implementation, if there is no branch vessel segment in the target vessel segment, the entire target vessel segment is taken as a vessel segment, and the middle portion thereof is taken as the preset position.

[0123] S504: For each branch blood vessel segment, obtain the blood flow of the branch blood vessel segment.

[0124] It should be explained that, for each branch blood vessel segment, the blood flow acquisition method introduced in the previous embodiment can be used to acquire the blood flow of the branch blood vessel segment.

[0125] S505: Determine a blood flow reserve fraction according to the blood flow of each branch vessel segment and the segmentation result.

[0126] In a possible implementation, the blood flow reserve fraction may be calculated by fluid mechanics simulation.

[0127] In specific implementation, a vascular three-dimensional model is established based on the contour information (i.e., vascular contour) obtained according to the segmentation of the vascular lumen, and the boundary conditions of the inlet and branch outlet are obtained based on the blood flow of the branch vascular segment. At the same time, the distal outlet pressure is preset (for example, in one possible implementation, the distal outlet pressure is set to 80 mmHg), so as to establish a complete fluid mechanics simulation model, and simulation is performed through the fluid mechanics simulation model to obtain the blood flow reserve fraction.

[0128] In another possible implementation, the blood flow reserve fraction may be calculated using a dimensionality reduction fluid dynamics model.

[0129] In specific implementation, multiple branch vessel segments of the target vessel segment can be divided into healthy vessel segments and stenotic vessel segments according to the vessel contour, and then the pressure losses (i.e., pressure drops) of the healthy vessel segments and the stenotic vessel segments are calculated respectively, and then the pressure drops of the healthy vessel segments and the stenotic vessel segments are summed to obtain the overall pressure drop of the target vessel segment, and finally the blood flow reserve fraction is further calculated according to the inlet pressure of the target vessel segment and the overall pressure drop.

[0130] Specifically, the pressure loss of a healthy blood vessel segment can be calculated according to the following formula:

[0131] ;

[0132] in, is the blood viscosity, is the blood density; is the average lumen area of ​​the vessel segment, is the inlet area of ​​the blood vessel segment, is the outlet area of ​​the vessel segment; is the blood flow rate of the blood vessel segment.

[0133] Furthermore, the pressure loss of the stenotic blood vessel segment can be calculated according to the following formula:

[0134] ;

[0135] in, is the length of the stenotic vessel segment, is the lumen area corresponding to the maximum stenosis, is the reference lumen area corresponding to the maximum stenosis, wherein the reference lumen area corresponding to the maximum stenosis is obtained by taking the average of the healthy lumen areas closest to the position.

[0136] Furthermore, the overall pressure drop of the target blood vessel segment can be calculated according to the following formula:

[0137] ;

[0138] in, is the overall pressure drop in the vessel segment; is the pressure drop of the healthy blood vessel segment in the blood vessel segment; is the pressure drop in the narrowed segment of the blood vessel.

[0139] The method provided in this embodiment obtains an OCT image sequence of a target vascular segment, and then performs vascular lumen segmentation and branch detection on the OCT image sequence to obtain segmentation results and branch detection results, and determines the preset positions of each branch vascular segment in the target vascular segment based on the branch detection results, and obtains the blood flow of each branch vascular segment for each branch vascular segment, thereby determining the blood flow reserve fraction based on the blood flow of each branch vascular segment and the segmentation result. In this way, based on the aforementioned method, the blood flow can be accurately obtained, which provides a good basis for calculating the blood flow reserve fraction. Furthermore, when the blood flow reserve fraction is obtained based on the blood flow, the blood flow velocity differences between individual patients are overcome, and the blood flow reserve fraction can be accurately calculated, and the calculated blood flow reserve fraction is closer to the actual measurement value.

[0140] Corresponding to the aforementioned embodiment of a blood flow acquisition method, the present application also provides an embodiment of a blood flow acquisition device.

[0141] The embodiment of a blood flow acquisition device of the present application can be applied to a blood flow acquisition device or integrated into an OCT device. The device embodiment can be implemented by software, or by hardware or a combination of software and hardware. Taking software implementation as an example, as a device in a logical sense, the processor of the blood flow acquisition device in which it is located reads the corresponding computer program instructions in the non-volatile memory into the memory and runs them. From the hardware level, if Figure 7 The figure is a hardware structure diagram of the blood flow acquisition device provided by the present application, in which the blood flow acquisition device is located. Figure 7 In addition to the processor, memory, network interface, and non-volatile memory shown, the blood flow acquisition device in the embodiment where the device is located may also include other hardware according to the actual function of the blood flow acquisition device, which will not be described in detail.

[0142] Figure 8 This is a schematic diagram of the structure of the blood flow acquisition device embodiment 1 provided in this application. Figure 8 , the device provided in this embodiment includes the acquisition module 810, the processing module 820, the determination module 830 and the calculation module 840; wherein;

[0143] The acquisition module 810 is used to acquire a plurality of spectral signals obtained by OCT scanning at a preset position of the blood vessel segment to be measured within a preset time period;

[0144] The processing module 820 is used to traverse the multiple spectral signals in sequence starting from the second spectral signal of the multiple spectral signals;

[0145] The determination module 830 is used to determine the phase difference between the current target spectrum signal and the previous spectrum signal at any position within the scanning range of the OCT scan, and obtain the phase difference of the target spectrum signal corresponding to the position;

[0146] The determination module 830 is used to calculate the blood flow corresponding to the target spectral signal by using the predetermined functional relationship between the blood flow, the flushing agent flow and the phase difference, according to the light source wavelength, sampling frame rate, angle between the light emitting direction and the blood flow direction, flushing agent flow, and all phase differences of the target spectral signal corresponding to all positions within the scanning range of the OCT system; wherein the predetermined functional relationship between the blood flow, the flushing agent flow and the phase difference is determined by a first functional relationship between the fluid flow and the fluid flow velocity at any position within the scanning range, a second functional relationship between the fluid flow velocity at any position within the scanning range and the phase difference and the refractive index of the mixed fluid after the blood and the flushing agent are mixed, a third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed, the fluid flow, the flushing agent flow, and the functional relationship between the fluid flow, the flushing agent flow, and the blood flow; the third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed, the fluid flow, and the flushing agent flow is determined according to the Lorentz equation;

[0147] The calculation module 840 is used to calculate the blood flow of the blood vessel segment to be measured according to the blood flow corresponding to all target spectral signals.

[0148] The device provided in this embodiment can be used to perform Figure 1 The steps, specific implementation principles and implementation processes of the method embodiment shown are similar and will not be repeated here.

[0149] Please continue to refer to Figure 7 The present application also provides a blood flow acquisition device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of any one of the methods provided in the first aspect of the present application are implemented.

[0150] The present application also provides a computer-readable storage medium having a computer program stored thereon, and when the program is executed by a processor, the steps of any one of the methods provided in the present application are implemented.

[0151] The implementation process of the functions and effects of each unit in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, and will not be repeated here.

[0152] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present application scheme. A person of ordinary skill in the art can understand and implement it without paying any creative work.

[0153] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for obtaining blood flow, characterized in that: The method comprises: Acquire multiple spectral signals obtained by OCT scanning at a preset position of the blood vessel segment to be measured within a preset time period; Starting from the second spectral signal of the multiple spectral signals, the multiple spectral signals are traversed in sequence; for any position within the scanning range of the OCT scan, a phase difference between the currently traversed target spectral signal and the previous spectral signal at the position is determined to obtain the phase difference of the target spectral signal corresponding to the position; The blood flow corresponding to the target spectral signal is calculated by using the predetermined functional relationship between the blood flow, the flushing agent flow and the phase difference, according to the light source wavelength, sampling frame rate, angle between the light emitting direction and the blood flow direction, flushing agent flow of the OCT system corresponding to the OCT scan, and all phase differences of the target spectral signal corresponding to all positions within the scanning range; wherein the predetermined functional relationship between the blood flow, the flushing agent flow and the phase difference is jointly determined by a first functional relationship between the fluid flow and the fluid flow velocity at any position within the scanning range, a second functional relationship between the fluid flow velocity at any position within the scanning range and the phase difference and the refractive index of the mixed fluid after the blood and the flushing agent are mixed, a third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed, the fluid flow, the flushing agent flow, and the functional relationship between the fluid flow, the flushing agent flow and the blood flow; the third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed, the fluid flow, and the flushing agent flow is determined according to the Lorentz equation; The blood flow rate of the blood vessel segment to be measured is calculated according to the blood flow rates corresponding to all target spectral signals.

2. The method according to claim 1, characterized in that The method for determining the predetermined functional relationship between the blood flow rate, the flushing agent flow rate and the phase difference comprises: According to the Lorentz-Lorentz equation, a third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed and the fluid flow rate and the flushing agent flow rate is determined; wherein the constant term in the third functional relationship is related to the refractive index of the blood, the refractive index of the flushing agent, the molar volume of the blood and the molar volume of the flushing agent; Substituting the third functional relationship into the second functional relationship of the fluid flow rate and phase difference at any position within the scanning range and the refractive index of the mixed fluid after the blood and the flushing agent are mixed, to obtain an intermediate functional relationship; The functional relationship between the blood flow rate, the flushing agent flow rate and the phase difference is determined based on the intermediate functional relationship, the first functional relationship between the fluid flow rate and the fluid flow rate at any position within the scanning range, and the functional relationship between the fluid flow rate, the flushing agent flow rate and the blood flow rate.

3. The method according to claim 2, characterized in that According to the Lorentz-Lorentz equation, the third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed and the fluid flow rate and the flushing agent flow rate is determined, including: Determining, based on the molar volume of the blood and the molar volume of the flushing agent, a fourth functional relationship between the molar fraction of the blood and the flushing agent flow rate and the fluid flow rate, and a fifth functional relationship between the molar fraction of the flushing agent and the flushing agent flow rate and the fluid flow rate, respectively; Substituting the fourth functional relationship and the fifth functional relationship into the Lorentz equation, a third functional relationship between the refractive index of the mixture of the blood and the flushing agent and the fluid flow rate and the flushing agent flow rate is obtained.

4. The method according to claim 1, characterized in that: The step of calculating the blood flow rate of the blood vessel segment to be measured according to the blood flow rates corresponding to all target spectral signals includes: Calculate the average value of blood flow corresponding to all current spectral signals; The average value is determined as the blood flow rate of the blood vessel segment to be measured.

5. The method according to claim 1, characterized in that The preset duration is equal to at least one cardiac cycle.

6. The method according to claim 5, characterized in that The cardiac cycle is calibrated by X-ray angiography or electrocardiogram.

7. A method for obtaining blood flow reserve fraction, characterized in that: The method comprises: Acquire an OCT image sequence of the target blood vessel segment; Performing blood vessel lumen segmentation and branch detection on the OCT image sequence respectively to obtain a segmentation result and a branch detection result; Determining the preset position of each branch blood vessel segment in the target blood vessel segment according to the branch detection result; For each branch blood vessel segment, using the method according to any one of claims 1 to 6 to obtain the blood flow of the branch blood vessel segment; The blood flow reserve fraction is determined according to the blood flow of each branch vessel segment and the segmentation result.

8. A blood flow acquisition device, characterized in that: The device includes an acquisition module, a processing module, a determination module and a calculation module; wherein, The acquisition module is used to acquire a plurality of spectral signals obtained by OCT scanning at a preset position of the blood vessel segment to be measured within a preset time period; The processing module is used to traverse the multiple spectral signals in sequence starting from the second spectral signal of the multiple spectral signals; The determination module is used to determine the phase difference between the current target spectrum signal and the previous spectrum signal at any position within the scanning range of the OCT scan, and obtain the phase difference of the target spectrum signal corresponding to the position; The determination module is used to calculate the blood flow corresponding to the target spectral signal by using the predetermined functional relationship between the blood flow, the flushing agent flow and the phase difference, according to the light source wavelength, sampling frame rate, angle between the light emitting direction and the blood flow direction, flushing agent flow of the OCT system corresponding to the OCT scan, and all phase differences of the target spectral signal corresponding to all positions within the scanning range; wherein the predetermined functional relationship between the blood flow, the flushing agent flow and the phase difference is determined by a first functional relationship between the fluid flow and the fluid flow velocity at any position within the scanning range, a second functional relationship between the fluid flow velocity at any position within the scanning range and the phase difference and the refractive index of the mixed fluid after the blood and the flushing agent are mixed, a third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed, the fluid flow, the flushing agent flow, and the functional relationship between the fluid flow, the flushing agent flow and the blood flow; the third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed, the fluid flow, the flushing agent flow and the blood flow; the third functional relationship between the refractive index of the mixed fluid after the blood and the flushing agent are mixed, the fluid flow, the flushing agent flow and the blood flow is determined according to the Lorentz equation; The calculation module is used to calculate the blood flow of the blood vessel segment to be measured according to the blood flow corresponding to all target spectral signals.

9. A blood flow acquisition device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method according to any one of claims 1 to 6 when executing the program.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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