Method of determining hemodynamic parameters, ultrasound device and computer storage medium

Abstract

The application discloses a method for determining hemodynamic parameters, an ultrasonic device and a computer storage medium. The method comprises the following steps: emitting ultrasonic beams to a target region comprising a blood vessel along at least two directions; receiving ultrasonic echoes to obtain ultrasonic echo signals; determining a velocity component of the velocity of blood flow in each of the at least two directions according to the ultrasonic echo signals; determining a vector velocity of the blood flow in the blood vessel according to the velocity components; determining a function of the change of the cross-sectional area of the blood vessel with time; and determining the blood flow per unit time according to the function of the change of the cross-sectional area of the blood vessel with time and the vector velocity. It can be seen that, in the process of calculating hemodynamic parameters such as blood flow and blood vessel wall shear stress, the application considers the change of the cross-sectional area of the blood vessel and the change of the position of the blood vessel wall caused by the change of the diameter of the blood vessel, so that the calculated hemodynamic parameters such as blood flow and blood vessel wall shear stress are more accurate.

Description

Technical Field

[0001] This invention relates to the medical field, and more specifically to a method for determining hemodynamic parameters, an ultrasound device, and a computer storage medium. Background Technology

[0002] In the measurement of hemodynamic parameters, traditional methods such as pulsed wave doppler (PW) are based on angle-corrected velocities, and the measurements are made on the following assumptions: (1) blood flow is laminar; (2) the diameter of the blood vessel is constant. However, in reality, blood flow may contain eddies or turbulence, especially when measuring narrow arteries; in addition, the diameter of the blood vessel may change with different phases of the cardiac cycle.

[0003] Taking blood flow as an example of a hemodynamic parameter, when measuring blood flow, the vessel diameter generally increases during systole and decreases during diastole, leading to changes in the vessel's cross-sectional area. Therefore, using a constant vessel diameter will result in inaccurate blood flow measurements. Furthermore, if the blood flow is not laminar, velocity can only be corrected empirically; moreover, if it is not laminar, not only is the actual velocity direction unknown, but the velocity direction may also differ at different locations along the diameter. All of these factors combined contribute to inaccurate blood flow measurements.

[0004] Taking the hemodynamic parameter of wall shear stress (WSS) as an example, when measuring WSS, the vessel diameter generally increases during systole and decreases during diastole. As the vessel diameter changes, the position of the vessel wall also changes. In other words, the location of the WSS measurement point changes with different phases of the cardiac cycle. Therefore, using a constant vessel diameter will lead to inaccurate WSS measurements. Furthermore, if the blood flow is not laminar, the velocity component parallel to the vessel wall cannot be obtained using traditional methods, making it impossible to calculate WSS. Summary of the Invention

[0005] This invention provides a method for determining hemodynamic parameters, an ultrasound device, and a computer storage medium.

[0006] In a first aspect, a method for determining hemodynamic parameters, including blood flow rate, is provided, the method comprising:

[0007] A first ultrasound beam is emitted toward a target area, including blood vessels, in at least two directions;

[0008] Receive the ultrasonic echo of the first ultrasonic beam returning from the target area to obtain ultrasonic echo signals in each of the at least two directions.

[0009] Based on the ultrasound echo signals along each of the at least two directions, determine the velocity component of the blood flow in the blood vessel along each of the at least two directions;

[0010] The vector velocity of blood flow in the blood vessel is determined based on the velocity components in each of the at least two directions.

[0011] Determine the function of how the cross-sectional area of ​​the blood vessel changes over time;

[0012] The blood flow per unit time is determined based on the function of the cross-sectional area changing over time and the vector velocity.

[0013] Secondly, a method for calculating hemodynamic parameters, including blood flow rate, is provided. The method includes:

[0014] A first ultrasound beam is emitted toward a target area, which includes blood vessels;

[0015] Receive the ultrasonic echo of the first ultrasonic beam returning from the target area to obtain an ultrasonic echo signal;

[0016] Based on the ultrasound echo signal, the vector velocity of blood flow in the blood vessel is determined;

[0017] Determine the function of how the cross-sectional area of ​​the blood vessel changes over time;

[0018] The blood flow per unit time is determined based on the function of the cross-sectional area changing over time and the vector velocity.

[0019] Thirdly, a method for calculating hemodynamic parameters, including blood flow rate, is provided, the method comprising:

[0020] An ultrasound beam is emitted toward a target area, which includes blood vessels;

[0021] Receive the ultrasonic echo of the ultrasonic beam returning from the target area to obtain the ultrasonic echo signal;

[0022] Based on the ultrasound echo signal, the average velocity of the blood flow at the sampling gate in the blood vessel along the normal direction of the cross-section of the blood vessel is determined.

[0023] Determine the function of how the cross-sectional area of ​​the blood vessel changes over time;

[0024] The blood flow rate per unit time is determined based on the function of the cross-sectional area changing over time and the average velocity of the blood flow.

[0025] Fourthly, a method for measuring hemodynamic parameters, including vessel wall shear stress or vessel wall shear rate, is provided. This method includes:

[0026] A first ultrasound beam is emitted toward a target area, including blood vessels, in at least two directions;

[0027] Receive the ultrasonic echo of the first ultrasonic beam returning from the target area to obtain ultrasonic echo signals in each of the at least two directions.

[0028] Based on the ultrasound echo signals along each of the at least two directions, determine the velocity component of the blood flow in the blood vessel along each of the at least two directions;

[0029] The vector velocity of blood flow in the blood vessel is determined based on the velocity components in each of the at least two directions.

[0030] Determine the position of the measurement points on the blood vessel wall in each frame;

[0031] The shear stress or shear rate of the blood vessel wall is determined based on the position of the measurement point in each frame and the vector velocity.

[0032] Fifthly, a method for measuring hemodynamic parameters, including vessel wall shear stress or vessel wall shear rate, is provided. This method includes:

[0033] A first ultrasound beam is emitted toward a target area, which includes blood vessels;

[0034] Receive the ultrasonic echo of the first ultrasonic beam returning from the target area to obtain an ultrasonic echo signal;

[0035] Based on the ultrasound echo signal, the vector velocity of blood flow in the blood vessel is determined;

[0036] Determine the position of the measurement points on the blood vessel wall in each frame;

[0037] The shear stress or shear rate of the blood vessel wall is determined based on the position of the measurement point in each frame and the vector velocity.

[0038] Sixthly, a method for measuring hemodynamic parameters, including vessel wall shear stress or vessel wall shear rate, is provided, the method comprising:

[0039] An ultrasound beam is emitted toward a target area, which includes blood vessels;

[0040] Receive the ultrasonic echo of the ultrasonic beam returning from the target area to obtain the ultrasonic echo signal;

[0041] Determine the diameter of the cross-section of the blood vessel corresponding to the measurement point on the blood vessel wall in each frame;

[0042] Based on the ultrasound echo signal, determine the maximum velocity of blood flow at the measurement point on the diameter of the cross-section of the blood vessel in each frame;

[0043] The shear stress or shear rate of the blood vessel wall is determined based on the diameter of the cross-section of the blood vessel corresponding to the measurement point in each frame and the maximum velocity value.

[0044] In a seventh aspect, an ultrasonic device is provided, comprising:

[0045] Ultrasonic probe;

[0046] A transmit / receive selection switch is used to excite the ultrasound probe to emit a first ultrasound beam toward a target area, including blood vessels, via a transmit circuit in at least two directions, and to receive the ultrasound echo of the first ultrasound beam returning from the target area.

[0047] Memory, used to store programs executed by the processor;

[0048] Processor, used for:

[0049] Based on the ultrasonic echo, ultrasonic echo signals are obtained along each of the at least two directions;

[0050] Based on the ultrasound echo signals along each of the at least two directions, determine the velocity component of the blood flow in the blood vessel along each of the at least two directions;

[0051] The vector velocity of blood flow in the blood vessel is determined based on the velocity components in each of the at least two directions.

[0052] Determine the function of how the cross-sectional area of ​​the blood vessel changes over time;

[0053] The blood flow per unit time is determined based on the function of the cross-sectional area changing over time and the vector velocity.

[0054] Eighthly, an ultrasonic device is provided, comprising:

[0055] Ultrasonic probe;

[0056] A transmit / receive selection switch is used to excite the ultrasound probe to emit a first ultrasound beam toward a target area, including blood vessels, via a transmit circuit in at least two directions, and to receive the ultrasound echo of the first ultrasound beam returning from the target area.

[0057] Memory, used to store programs executed by the processor;

[0058] Processor, used for:

[0059] Based on the ultrasonic echo, ultrasonic echo signals are obtained along each of the at least two directions;

[0060] Based on the ultrasound echo signals along each of the at least two directions, determine the velocity component of the blood flow in the blood vessel along each of the at least two directions;

[0061] The vector velocity of blood flow in the blood vessel is determined based on the velocity components in each of the at least two directions.

[0062] Determine the position of the measurement points on the blood vessel wall in each frame;

[0063] The shear stress or shear rate of the blood vessel wall is determined based on the position of the measurement point in each frame and the vector velocity.

[0064] Ninthly, an ultrasonic device is provided, comprising:

[0065] Ultrasonic probe;

[0066] A transmit / receive selection switch is used to excite the ultrasound probe to emit an ultrasound beam toward a target area via the transmit circuit, and to receive the ultrasound echo of the ultrasound beam returning from the target area, including blood vessels.

[0067] Memory is used to store programs executed by the processor;

[0068] Processor, used for:

[0069] Obtaining ultrasonic echo signals based on ultrasonic echo;

[0070] Based on the ultrasound echo signal, determine the average velocity of the blood flow at the sampling gate in the blood vessel along the normal direction of the cross-section of the blood vessel.

[0071] Determine the function of change of the cross-sectional area of ​​the blood vessel over time;

[0072] The blood flow rate per unit time is determined based on the function of cross-sectional area changing with time and the average velocity of blood flow.

[0073] In a tenth aspect, an ultrasonic device is provided, comprising:

[0074] Ultrasonic probe;

[0075] A transmit / receive selection switch is used to excite the ultrasound probe to emit an ultrasound beam toward a target area via a transmit circuit, and to receive the ultrasound echo of the ultrasound beam returning from the target area, which includes blood vessels.

[0076] Memory, used to store programs executed by the processor;

[0077] Processor, used for:

[0078] The ultrasonic echo signal is obtained based on the ultrasonic echo.

[0079] Determine the diameter of the cross-section of the blood vessel corresponding to the measurement point on the blood vessel wall in each frame;

[0080] Based on the ultrasound echo signal, determine the maximum velocity of blood flow at the measurement point on the diameter of the cross-section of the blood vessel in each frame;

[0081] The shear stress or shear rate of the blood vessel wall is determined based on the diameter of the cross-section of the blood vessel corresponding to the measurement point in each frame and the maximum velocity value.

[0082] Eleventhly, a computer storage medium is provided, on which a computer program is stored, which, when executed by a computer or processor, implements the steps of the method described in any one of the first to sixth aspects.

[0083] Therefore, in calculating hemodynamic parameters such as blood flow and vessel wall shear stress or vessel wall shear rate, the embodiments of the present invention take into account the changes in vessel cross-sectional area and vessel wall position caused by changes in vessel diameter, thereby making the calculated hemodynamic parameters such as blood flow and vessel wall shear stress or vessel wall shear rate more accurate. Attached Figure Description

[0084] The above and other objects, features, and advantages of the present invention will become more apparent from the more detailed description of the embodiments of the invention in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same parts or steps.

[0085] Figure 1 This is a structural block diagram of an ultrasonic device;

[0086] Figure 2 This is a schematic flowchart of a method for determining hemodynamic parameters according to an embodiment of the present invention;

[0087] Figure 3 This is another schematic flowchart of the method for determining hemodynamic parameters according to an embodiment of the present invention;

[0088] Figure 4 This is another schematic flowchart of the method for determining hemodynamic parameters according to an embodiment of the present invention;

[0089] Figure 5This is a schematic diagram of a longitudinal section of a blood vessel according to an embodiment of the present invention;

[0090] Figure 6 This is a schematic diagram of a pixel in an embodiment of the present invention;

[0091] Figure 7 (a) and (b) are schematic diagrams of the closed lines in an embodiment of the present invention;

[0092] Figure 8 (a) and (b) are schematic diagrams of the velocity components of the vector velocity in the normal direction according to an embodiment of the present invention;

[0093] Figure 9 This is another schematic flowchart of the method for determining hemodynamic parameters according to an embodiment of the present invention;

[0094] Figure 10 This is another schematic flowchart of the method for determining hemodynamic parameters according to an embodiment of the present invention;

[0095] Figure 11 This is another schematic flowchart of the method for determining hemodynamic parameters according to an embodiment of the present invention;

[0096] Figure 12 This is another schematic flowchart of the method for determining hemodynamic parameters according to an embodiment of the present invention;

[0097] Figure 13 This is a schematic diagram of a measurement point on the blood vessel wall according to an embodiment of the present invention;

[0098] Figure 14 This is another schematic flowchart of the method for determining hemodynamic parameters according to an embodiment of the present invention;

[0099] Figure 15 This is a schematic diagram of the velocity component of the vector velocity in the direction parallel to the blood vessel wall according to an embodiment of the present invention. Detailed Implementation

[0100] This invention provides an ultrasound device that can obtain more accurate hemodynamic parameters.

[0101] like Figure 1 The diagram shows a structural block diagram of an ultrasonic device. The ultrasonic device 10 includes an ultrasonic probe 110, a transmit / receive selection switch 120, a memory 130, a processor 140, and a display 150. The transmit / receive selection switch 120 can excite the ultrasonic probe 110 to emit an ultrasonic beam towards a target area, and the ultrasonic probe 110 can receive the ultrasonic echo of the ultrasonic beam returning from the target area. The processor 140 can obtain the ultrasonic echo signal based on the ultrasonic echo of the ultrasonic beam and process the ultrasonic echo signal.

[0102] Exemplarily, the transmit / receive selection switch 120 can excite the ultrasound probe 110 to emit a first ultrasound beam toward a target region, including a blood vessel, along at least two directions, and receive ultrasound echoes of the first ultrasound beam returning from the target region via the ultrasound probe 110. The processor 140 can, based on the ultrasound echoes, obtain ultrasound echo signals along each of the at least two directions; determine the velocity components of the blood flow in the blood vessel along each of the at least two directions based on the ultrasound echo signals along each of the at least two directions; determine the vector velocity of the blood flow in the blood vessel based on the velocity components along each of the at least two directions; determine the function of change of the cross-sectional area of ​​the blood vessel over time; and determine the blood flow rate per unit time based on the function of change of the cross-sectional area over time and the vector velocity. A more detailed description can be found in subsequent embodiments of this specification.

[0103] Alternatively, by way of example, the transmit / receive selection switch 120 can excite the ultrasound probe 110 to emit a first ultrasound beam toward a target region, including a blood vessel, along at least two directions, and receive ultrasound echoes of the first ultrasound beam returning from the target region via the ultrasound probe 110. The processor 140 can, based on the ultrasound echoes, obtain ultrasound echo signals along each of the at least two directions; determine the velocity components of the blood flow in the blood vessel along each of the at least two directions based on the ultrasound echo signals along each of the at least two directions; determine the vector velocity of the blood flow in the blood vessel based on the velocity components along each of the at least two directions; determine the position of a measurement point on the blood vessel wall in each frame; and determine the blood vessel wall shear stress or wall shear rate (WSR) based on the position of the measurement point in each frame and the vector velocity.

[0104] For example, processor 140 can transmit a second ultrasonic beam to a target area and receive the ultrasonic echo of the second ultrasonic beam returning from the target area to obtain an ultrasonic echo signal; based on the ultrasonic echo signal, an ultrasonic image of the target area can be obtained. For example, the ultrasonic echo signal can be processed by beamforming, orthogonal demodulation, wall filtering, etc. The ultrasonic image obtained by processor 140 can be stored in memory 130. Furthermore, the ultrasonic image can be displayed on display 150. Optionally, the display 150 can also display hemodynamic parameters of the blood vessel, such as blood flow, vessel wall shear stress, or vessel wall shear rate.

[0105] Optionally, the display 150 in the ultrasound device 10 can be a touch screen, an LCD screen, or the like; or the display 150 can be an independent display device such as an LCD screen or a television, separate from the ultrasound device 10; or the display 150 can be the screen of an electronic device such as a smartphone or tablet, etc. The number of displays 150 can be one or more.

[0106] Optionally, the memory 130 in the ultrasonic device 10 can be a flash memory card, solid-state memory, hard disk, etc. It can be volatile memory and / or non-volatile memory, removable memory and / or non-removable memory, etc.

[0107] Optionally, the processor 140 in the ultrasonic device 10 can be implemented by software, hardware, firmware, or any combination thereof. It can be implemented by circuits, one or more application-specific integrated circuits (ASICs), one or more general-purpose integrated circuits, one or more microprocessors, one or more programmable logic devices, or any combination of the foregoing circuits and / or devices, or other suitable circuits or devices, so that the processor 140 can perform the corresponding steps of the methods in the various embodiments of this specification.

[0108] It should be understood that Figure 1 The components included in the illustrated ultrasonic device 10 are merely illustrative and may include more or fewer components. For example, the ultrasonic device 10 may also include input devices such as a keyboard, mouse, scroll wheel, trackball, etc., and / or output devices such as a printer, in addition to the display 150. The corresponding external input / output ports may be wireless communication modules, wired communication modules, or a combination of both. External input / output ports may also be implemented based on USB, bus protocols such as CAN, and / or wired network protocols. This invention is not limited in this respect.

[0109] This invention provides a method for determining hemodynamic parameters, which may include blood flow rate. A flowchart of this method is shown below. Figure 2 As shown, the method includes:

[0110] S110, determine the function of change of the cross-sectional area of ​​the blood vessel over time;

[0111] S120, calculate the vector velocity of blood flow in the blood vessel;

[0112] S130, the blood flow per unit time is determined based on the function of the cross-sectional area changing with time and the vector velocity.

[0113] For example, in S120, vector velocity can be calculated based on vector blood flow imaging technology. This solves the problem of non-laminar velocity measurement, thereby accurately obtaining the velocity components of the vector velocity at each point through the cross-section along the normal direction of the cross-section during blood flow measurement, and also accurately obtaining the velocity components of the vector velocity at each point parallel to the blood vessel wall.

[0114] One implementation method is to calculate the vector velocity using a multi-angle deflection emission approach, see [link to relevant documentation]. Figure 3 S120 may include: S101 to S104.

[0115] S101, emitting a first ultrasound beam toward a target area, including blood vessels, in at least two directions;

[0116] S102, receive the ultrasonic echo of the first ultrasonic beam returning from the target area to obtain ultrasonic echo signals along each of the at least two directions.

[0117] S103, Based on the ultrasound echo signals along each of the at least two directions, determine the velocity component of the blood flow velocity in the blood vessel along each of the at least two directions;

[0118] S104, determine the vector velocity of blood flow in the blood vessel based on the velocity components in each of the at least two directions;

[0119] S110, determine the function of the cross-sectional area of ​​the blood vessel as a function of time;

[0120] S130, the blood flow per unit time is determined based on the function of the cross-sectional area changing with time and the vector velocity.

[0121] For example, at least two directions may include a first direction and a second direction, which have different deflection angles. For instance, the first direction is parallel to the normal direction of the array element arrangement, and the second direction forms an acute angle with the normal direction of the array element arrangement. By controlling the transmission delay of each array element, ultrasonic beams with different deflection angles can be obtained. Based on the ultrasonic echo signals obtained from the ultrasonic beams with different deflection angles, the velocity components of the blood flow corresponding to different deflection angles can be obtained, and the vector velocity of the blood flow can be obtained based on the velocity components at different deflection angles. Taking the calculation of the vector velocity of blood flow near a measurement point using ultrasound beams with two deflection angles as an example, the first velocity component of the blood flow (or red blood cells) near the measurement point along the first deflection angle is obtained from the ultrasound echo signal corresponding to the ultrasound beam with the first deflection angle. The second velocity component of the blood flow at the same point along the second deflection angle is obtained from the ultrasound echo signal corresponding to the ultrasound beam with the second deflection angle. The first velocity component is represented by a first vector, whose magnitude is the velocity value corresponding to the first velocity component, and whose direction is the direction corresponding to the first deflection angle. The second velocity component is represented by a second vector, whose magnitude is the velocity value corresponding to the second velocity component, and whose direction is the direction corresponding to the second deflection angle. The starting point of the first vector and the second vector (such as the position of the point corresponding to the blood flow) is the same point. The vector velocity of a point near the measurement point corresponding to the blood flow can be determined based on the intersection of the first orthogonal line at the endpoint of the first vector and the second orthogonal line at the endpoint of the second vector. The magnitude and direction of the vector velocity of the point near the measurement point corresponding to the blood flow are the same as the magnitude and direction of the vector from the starting point of the first and second vectors to the intersection of the first and second orthogonal lines.

[0122] As another implementation method, the vector velocity can be calculated based on the speckle tracking method, the transverse wave oscillation method, or the multi-angle deflection receiver method. See [link to relevant documentation]. Figure 4 S120 may include S105 to S107.

[0123] S105, emit a first ultrasound beam toward a target area, which includes blood vessels;

[0124] S106, Receive the ultrasonic echo of the first ultrasonic beam returning from the target area to obtain an ultrasonic echo signal;

[0125] S107, Based on the ultrasound echo signal, determine the vector velocity of blood flow in the blood vessel;

[0126] S110, determine the function of the cross-sectional area of ​​the blood vessel as a function of time;

[0127] S130, the blood flow per unit time is determined based on the function of the cross-sectional area changing with time and the vector velocity.

[0128] For example, S107 may include: tracking the ultrasound echo signal using a speckle tracking method to obtain the vector velocity of blood flow in the blood vessel. Optionally, this can be achieved using a normalized cross-correlation method; or to reduce computational load, a sum of absolute differences (SAD) method can be used; or to reduce complexity, a block sum pyramid algorithm can be used; or to reduce errors caused by echo decorrelation, an ensemble tracking method can be used; and so on.

[0129] Alternatively, for example, S107 may include: determining the transverse and longitudinal velocities of blood flow in the blood vessel based on the ultrasound echo signal, and obtaining the vector velocity of blood flow in the blood vessel based on the transverse and longitudinal velocities. Optionally, the longitudinal velocity can be obtained using a conventional calculation method based on the Doppler principle, or the transverse velocity can be calculated based on the autocorrelation method by generating a transversely oscillating ultrasound field.

[0130] Alternatively, exemplarily, S106 may include: receiving ultrasound echoes from a first ultrasound beam returning from a target area along at least two directions to obtain ultrasound echo signals along each of the at least two directions; correspondingly, S107 may include: determining the velocity component of the blood flow velocity in the blood vessel along each of the at least two directions based on the ultrasound echo signals in each of the at least two directions; and determining the vector velocity of the blood flow in the blood vessel based on the velocity components in each of the at least two directions. Wherein, the at least two directions have different deflection angles, and the method for determining the vector velocity by multi-angle deflection reception can be referred to... Figure 3 The method for determining the vector velocity by multi-angle deflection emission in the illustrated embodiment is for understanding purposes only and will not be elaborated upon here.

[0131] In addition, it should be noted that, although Figure 2 The process of determining the vector velocity, S120, is executed after S110. Figure 3 The process of determining the vector velocity, S101 to S104, is shown to be executed before S110. Figure 4 The process of determining the vector velocity, S105 to S107, is shown to be executed before S110. However, the specific order of the two processes, S110 and S120, is not limited in this embodiment of the invention.

[0132] Considering that the diameter of a blood vessel is not a constant value but varies with the phases of the cardiac cycle, its cross-sectional area also varies with time. In this embodiment of the invention, the cross-sectional area of ​​the blood vessel at each moment is determined in S110, where a moment can be represented as a frame.

[0133] It is understood that embodiments of the present invention may further include: transmitting a second ultrasonic beam toward a target area and receiving the ultrasonic echo of the second ultrasonic beam returning from the target area to obtain an ultrasonic echo signal; and processing the ultrasonic echo signal to obtain an ultrasonic image of the target area. The processing may include beamforming, orthogonal demodulation, filtering, etc.

[0134] Optionally, it may also include: displaying ultrasound images of blood vessels and representing hemodynamic parameters in the ultrasound images.

[0135] In one implementation, S110 can determine the diameter of the blood vessel and then determine the cross-sectional area based on the diameter. In another implementation, S110 can determine the position of the blood vessel wall and then determine the cross-sectional area. In yet another implementation, S110 can directly determine the cross-sectional area. These will be explained in detail below.

[0136] In one embodiment, the target region includes a longitudinal section of a blood vessel, where the longitudinal section refers to a cross-section obtained by scanning along the longitudinal axis of the blood vessel. S110 may include: transmitting a third ultrasound beam to the target region; receiving the ultrasound echo of the third ultrasound beam returning from the target region to obtain an ultrasound echo signal; obtaining multiple frames of longitudinal section ultrasound images of the blood vessel based on the ultrasound echo signal corresponding to the third ultrasound beam; determining the diameter of the selected location of the blood vessel in each frame based on each frame of the multiple frames of longitudinal section ultrasound images; and determining the cross-sectional area of ​​the blood vessel in each frame based on the diameter. Optionally, the longitudinal section ultrasound image may be a two-dimensional grayscale image.

[0137] Determining the diameter of the selected location of the blood vessel in each frame can include: determining the diameter of the selected location of the blood vessel in each frame through image recognition; or, it can include: obtaining the diameter of the selected location of the blood vessel in each frame as measured by the user.

[0138] To determine the cross-sectional area of ​​a blood vessel corresponding to a specific frame t, a longitudinal cross-sectional ultrasound image of the blood vessel corresponding to that frame t can be obtained. For example, ... Figure 5 As shown.

[0139] To determine the cross-sectional area at a selected location, that location can be specified in the longitudinal section ultrasound image of the blood vessel. For example, a user can click or select the location of the blood vessel where the desired measurement is desired, referring to... Figure 5 It can obtain user information. Figure 5The user can click or select any point on the straight line shown. It is understood that the user can click or select one or more points. If it is a single point, the diameter at the selected location can refer to the diameter of the cross-section of the blood vessel containing that point. If it is multiple points, the diameter at the selected location can be the diameter of the cross-section of the blood vessels containing all those points.

[0140] The diameter at the selected location can then be determined using image recognition. Alternatively, the user can manually measure the diameter at the selected location.

[0141] Assuming the diameter of the selected location in frame t is d(t), the cross-sectional area A(t) of the selected location in frame t can be calculated based on this diameter. Specifically, A(t) = π × d(t) × d(t) / 4.

[0142] Similar to the process for frame t, the cross-sectional area of ​​the selected location at other times can also be obtained, thus showing the change of the cross-sectional area of ​​the selected location over time. Optionally, it can be represented as A(t), a function representing the change of the cross-sectional area of ​​the selected location over time t.

[0143] In one embodiment, the target region includes a cross-section of a blood vessel, where the cross-section refers to a section obtained by scanning along the transverse axis of the blood vessel. S110 may include: obtaining multiple frames of cross-sectional ultrasound images of the blood vessel based on the ultrasound echo signal corresponding to the first ultrasound beam; determining the cross-sectional area corresponding to each frame of the cross-sectional ultrasound images of the blood vessel at a selected location in each frame. Alternatively, S110 may include: transmitting a fourth ultrasound beam to the target region; receiving the ultrasound echo of the fourth ultrasound beam returning from the target region to obtain an ultrasound echo signal; obtaining multiple frames of cross-sectional ultrasound images of the blood vessel based on the ultrasound echo signal corresponding to the fourth ultrasound beam; determining the cross-sectional area corresponding to each frame of the cross-sectional ultrasound images of the blood vessel at a selected location in each frame. Optionally, the cross-sectional ultrasound images may be two-dimensional grayscale images.

[0144] For example, determining the cross-sectional area of ​​a selected location of a blood vessel in each frame may include: determining the cross-sectional area of ​​a selected location of a blood vessel in each frame through image recognition; or, it may include: obtaining the cross-sectional area of ​​a selected location of a blood vessel in each frame as measured by the user.

[0145] To determine the cross-sectional area of ​​a blood vessel corresponding to a certain frame t, a cross-sectional ultrasound image of the blood vessel corresponding to that frame t can be obtained. Specifically, a cross-sectional ultrasound image of the blood vessel at a selected location can be obtained.

[0146] As an example, the cross-sectional area at the selected location can be determined through image recognition. Optionally, if the cross-sectional ultrasound image includes multiple blood vessels, each blood vessel or the blood vessel at the selected location can be identified using image recognition, and then the cross-sectional area can be determined; alternatively, user specifications can be obtained, indicating which blood vessel is located at the selected location, and the cross-sectional area can be determined through image recognition based on the user specifications.

[0147] As another example, the cross-sectional area measured by the user can be obtained. For instance, a cross-section manually drawn by the user can be obtained, and then the area of ​​the user-drawn cross-section can be measured to determine the cross-sectional area at the selected location.

[0148] Alternatively, for example, determining the cross-sectional area of ​​a selected location of a blood vessel in each frame may include: for each frame of cross-sectional ultrasound image: determining a plurality of blood vessel wall pixels in the cross-sectional ultrasound image; constructing a closure line based on some or all of the plurality of blood vessel wall pixels; and determining the area of ​​the space enclosed by the closure line as the cross-sectional area.

[0149] Generally, in ultrasound images, the signal value at the tissue is usually greater than the signal value at the blood flow site, while the signal value of the blood vessel wall is even greater than that at the tissue site. Therefore, the blood vessel wall in the ultrasound image can be identified based on this.

[0150] Determining multiple blood vessel wall pixels in a cross-sectional ultrasound image can include: if the difference between the signal value of a certain pixel and the signal values ​​of several surrounding pixels of that certain pixel meets a preset condition, then that certain pixel is determined as a blood vessel wall pixel.

[0151] The preset condition may include: among the several differences obtained by subtracting the signal value of a certain pixel from the signal values ​​of several surrounding pixels, the ratio of the number of differences greater than a preset difference to the number of surrounding pixels is greater than a threshold. Optionally, the preset difference can be set based on the actual difference between the signal value of the blood vessel wall and the signal value at the tissue. Optionally, the threshold can be a value greater than 0 and less than 1, such as 0.2 or 0.5, etc.

[0152] Specifically, assuming that the number of surrounding pixels of a certain pixel in a cross-sectional ultrasound image (hereinafter referred to as the judgment point for convenience) is N, the difference between the signal value of the judgment point and the signal values ​​of these N surrounding pixels can be calculated to obtain N difference values. If the number of these N difference values ​​that is greater than a preset difference value is N1, and N1 / N is greater than a threshold, then it is indicated that the judgment point is a blood vessel wall pixel.

[0153] In this context, the distance between each surrounding pixel and the decision point is less than twice the distance between two adjacent pixels. In other words, the distance between the surrounding pixels and the decision point does not include any additional pixels.

[0154] Reference Figure 6 If the judgment point is a non-edge point (such as point P1), then the surrounding pixels of the judgment point include 8 (e.g., ... Figure 6 Within the dashed box containing point P1, there are 8 other points besides P1, i.e., N=8. If the judgment point is a non-corner edge point (such as point P2), then the surrounding pixels of this judgment point include 5 (e.g., ... Figure 6 Within the dashed box containing point P2, there are 5 other points besides P2, i.e., N=5. If the judgment point is a corner point (such as point P3), then the surrounding pixels of that judgment point include 3 (e.g., ...). Figure 6 The dashed box containing point P3 includes three other points besides P3, i.e., N = 3.

[0155] Optionally, different thresholds can be set for different types of decision points.

[0156] For example, for a non-edge point like point P1, a threshold can be set to 1 / 8 or 1 / 4. In this way, the signal value difference between the non-edge point and its eight surrounding points is calculated, resulting in eight difference values. If one or two of these eight differences are greater than the preset difference value, then the non-edge point is identified as a blood vessel wall pixel.

[0157] For example, for non-corner edge points such as point P2, a threshold can be set to 1 / 5 or 2 / 5. In this way, the signal value difference between the non-corner edge point and its five surrounding points is calculated, resulting in five difference values. If one or two of these five differences are greater than the preset difference value, then the non-corner edge point is identified as a blood vessel wall pixel.

[0158] For example, for a corner point like point P3, a threshold can be set to 1 / 3 or 2 / 3. Then, the signal values ​​of the corner point and its three surrounding points are calculated to obtain three difference values. If one or two of these three differences are greater than the preset difference value, the corner point is identified as a blood vessel wall pixel.

[0159] In this embodiment, when calculating the difference in signal values ​​between two different pixels, it is understood that if both pixels represent tissue or blood flow, the difference in signal values ​​will be less than a preset difference. Furthermore, it should be understood that this process may mistakenly identify tissue pixels as blood vessel wall pixels.

[0160] Furthermore, curve fitting or polylines can be used to connect some or all of the multiple blood vessel wall pixels to construct a closed line.

[0161] For example, when constructing a closed line, it can be achieved by connecting a blood vessel wall pixel to blood vessel wall pixels in its surrounding areas. If the line obtained by this connection method is not closed, it should be obtained through automatic or manual correction.

[0162] Specifically, we can find non-closed points and then connect the two closest non-closed points to obtain a closed line. A point is considered non-closed if only one of its surrounding points is a pixel representing the blood vessel wall. Figure 7 (a) shows two non-closed points. Connecting the two closest non-closed points can be done with a straight line, such as... Figure 7 As shown in (b), the two non-closed points can also be connected by fitting or by using other pixels between them, such as by a curve or a polyline. This invention is not limited in this respect.

[0163] Additionally, it is understandable that if a blood vessel wall pixel does not exist among several surrounding points, then this point is incorrectly identified as a blood vessel wall pixel. When constructing the closure line, it can be ignored or identified as a non-blood vessel wall pixel.

[0164] For example, when constructing a closed line, multiple blood vessel wall pixels can be connected sequentially to form a closed polyline. As one example, the closed polyline can be used as the closed line. As another example, the closed polyline can be smoothed by median filtering or other methods to obtain a smooth curve, and this smooth curve can be used as the closed line. This makes the result more accurate and stable.

[0165] For example, when constructing a closure line, a subset of blood vessel wall pixels can be selected from multiple blood vessel wall pixels, and then these subsets can be sequentially connected to form a closure polyline. As one example, this closure polyline can be used as the closure line; as another example, the closure polyline can be smoothed using methods such as median filtering to obtain a smooth curve, which can then be used as the closure line. This approach makes the results more accurate and stable.

[0166] Based on the above description, it can be understood that the shape of the closed line in the embodiments of the present invention can be irregular.

[0167] Furthermore, the cross-sectional area can be determined based on the number of pixels enclosed by the constructed closed line. For example, the cross-sectional area can be calculated by multiplying the number of pixels enclosed by the closed line by the area of ​​a single pixel. The area of ​​a single pixel is related to the ultrasound imaging device used to create the cross-sectional ultrasound image; alternatively, the area of ​​a single pixel can be calculated by measuring the distance between two adjacent pixels, the length and width of the pixel, and the coordinates of the pixel.

[0168] Alternatively, for example, determining the cross-sectional area of ​​a selected location of a blood vessel in each frame may include obtaining the corresponding cross-sectional area for the selected location of the blood vessel using a rectangular bar approximation method or a circular ring approximation method.

[0169] Specifically, the cross-section can be approximated as several rectangular strips of the same thickness, and the sum of the areas of each rectangular strip is taken as the cross-sectional area. Alternatively, the cross-section can be approximated as multiple circular rings of the same thickness, and the sum of the areas of each circular ring is taken as the cross-sectional area.

[0170] Therefore, in this embodiment of the invention, the cross-sectional area of ​​a blood vessel can be determined based on a longitudinal or cross-sectional ultrasound image. This allows for real-time determination of the cross-sectional area of ​​the blood vessel at various points in time, thus revealing the change in cross-sectional area over time.

[0171] For example, S130 may include: calculating the velocity component of the vector velocity along the normal direction of the cross-section of the blood vessel; and determining the blood flow rate per unit time based on the function of the cross-sectional area changing with time and the velocity component of the vector velocity along the normal direction of the cross-section of the blood vessel.

[0172] The schematic diagram for calculating the velocity component of the vector velocity in the normal direction is shown below. Figure 8 As shown in (a), the velocity components can be calculated by projecting the vector velocity onto the normal direction of the cross section.

[0173] As an example, the velocity component of the vector velocity along the normal direction of the cross-section of the blood vessel can be the velocity after angle correction for the current frame obtained by the PW method. For example, if the blood flow is laminar, it can be obtained by performing angle correction.

[0174] As another example, the velocity component along the normal direction of the blood vessel's cross-section can be the average of the normal components at various locations along the cross-section. For instance, if the blood flow is non-laminar, the vector velocity at different locations may also differ, such as in direction and / or magnitude. (See reference...) Figure 8 (b) The normal component at each location can be calculated, and then the velocity component along the normal direction can be determined by averaging and other algorithms. It should be understood that... Figure 8The magnitudes of the normal components shown in (b) are merely illustrative.

[0175] Blood flow can refer to the flow rate through the cross-section of a blood vessel per unit time. Alternatively, the velocity component of the vector velocity along the normal direction of the blood vessel's cross-section can be expressed as v. m (t). Therefore, the blood flow rate per unit time can be obtained using the following formula:

[0176]

[0177] Where T represents a time period, such as one minute, or a cardiac cycle. Thus, the cross-sectional area A(t) and the velocity component v can be used as the basis for... m (t) calculates the blood flow Q per unit time.

[0178] Furthermore, if blood flow is understood as the total flow through the cross-section of a blood vessel over a period of time, then it can be understood through… get.

[0179] Therefore, it can be seen that the embodiments of the present invention fully consider the instantaneous changes in the inner diameter of blood vessels when measuring blood flow, and determine the blood flow based on the changes in cross-sectional area over time, making the results more accurate.

[0180] exist Figures 2-4 In one embodiment, the hemodynamic parameters include blood flow rate, and the blood flow rate per unit time is obtained in S130, denoted as Q.

[0181] Furthermore, hemodynamic parameters may also include vessel wall shear stress or vessel wall shear rate, and after S130, vessel wall shear stress can be calculated based on blood flow. Specifically, after S130: the average diameter of the vessel per unit time is determined; based on the average blood flow and the average diameter per unit time, the average vessel wall shear stress or vessel wall shear rate per unit time is determined.

[0182] The mean diameter can be obtained by averaging the instantaneous diameters over a unit time T. This mean diameter can be called the average diameter over a unit time T, denoted as d. m .

[0183] The average shear stress of the blood vessel wall can be calculated using the following formula: Where μ represents the blood viscosity coefficient, Q represents the blood flow rate, and d m τ represents the mean diameter. m This represents the average shear stress of the blood vessel wall. It can be understood that the average shear stress τ of the blood vessel wall can also be represented as... m This is called the average shear stress of the blood vessel wall per unit time.

[0184] The mean shear rate of the blood vessel wall can be calculated using the following formula: Where Q represents blood flow, d m WSR represents the mean diameter. m This represents the mean shear rate of the vessel wall. Alternatively, the mean shear rate of the vessel wall (WSR) can also be understood as... m This is called the average shear rate of the blood vessel wall per unit time.

[0185] Alternatively, the hemodynamic parameters may further include vessel wall shear stress or vessel wall shear rate, and after S120 (such as S104 or S107), the calculation of vessel wall shear stress or vessel wall shear rate based on vector velocity may be included. Specifically, after S120, the following steps may be included: determining the position of the measurement point on the vessel wall in each frame; and determining the vessel wall shear stress or vessel wall shear rate based on the position of the measurement point in each frame and the vector velocity.

[0186] For example, the velocity component of the blood flow vector velocity near the measurement point along the tangent direction of that measurement point to the vessel wall can be determined; based on the position of the measurement point in each frame and the velocity component of the blood flow vector velocity near the measurement point along the tangent direction of that measurement point to the vessel wall, the vessel wall shear stress or vessel wall surface shear rate can be determined. For methods of calculating vessel wall shear stress or vessel wall surface shear rate, please refer to the following sections. Figures 10 to 12 Understand the content described.

[0187] This invention provides a method for determining hemodynamic parameters, which may include blood flow rate. A flowchart of this method is shown below. Figure 9 As shown, the method includes:

[0188] S140, emits an ultrasound beam toward a target area, which includes blood vessels;

[0189] S150 receives the ultrasonic echo of the ultrasonic beam returning from the target area to obtain the ultrasonic echo signal.

[0190] S160, based on the ultrasound echo signal, determine the average velocity of the blood flow at the sampling gate in the blood vessel along the normal direction of the cross-section of the blood vessel.

[0191] S170, determine the function of change of the cross-sectional area of ​​the blood vessel over time;

[0192] S180, the blood flow rate per unit time is determined based on the function of cross-sectional area changing with time and the average velocity of blood flow.

[0193] For example, S170 can be referred to the specific implementation described above in conjunction with S110, and will not be repeated here to avoid repetition.

[0194] For example, in S160, the conventional pulsed Doppler (PW) method can be used to obtain the average velocity of the blood flow at the sampling gate in the blood vessel along the normal direction of the cross-section of the blood vessel. It can be understood that for each frame of ultrasound echo signal, the average velocity of the blood flow corresponding to that frame is obtained, and thus the average velocity of the blood flow along the normal direction of the cross-section of the blood vessel for each frame can be obtained, which can be expressed as v m (t).

[0195] For example, S180 may include: obtaining the blood flow rate per unit time by the following formula:

[0196]

[0197] Where T represents unit time, such as one minute, or one cardiac cycle. Where Q represents blood flow per unit time. Where A(t) represents the function of the cross-sectional area obtained from S170 changing with time.

[0198] Therefore, it can be seen that the embodiments of the present invention fully consider the change of cross-sectional area over time caused by the instantaneous change of the inner diameter of the blood vessel when measuring blood flow, so that the blood flow result obtained per unit time is more accurate.

[0199] For example, hemodynamic parameters may also include vessel wall shear stress. Therefore, after S180, the process may further include calculating the vessel wall shear stress based on blood flow. Specifically, after S180: the average diameter of the vessel per unit time is determined; based on the average blood flow and the average diameter per unit time, the average vessel wall shear stress per unit time is determined. For an example, please refer to the description of the process for determining the vessel wall shear stress after S130 above; it will not be repeated here.

[0200] This invention also provides a method for determining hemodynamic parameters, which may include vessel wall shear stress or vessel wall shear rate. A flowchart of this method is shown below. Figure 10 As shown, the method includes:

[0201] S210, determine the position of the measurement point on the blood vessel wall in each frame;

[0202] S220, calculate the vector velocity of blood flow in the blood vessel;

[0203] S230, determine the shear stress or shear rate of the blood vessel wall based on the position of the measurement point in each frame and the vector velocity.

[0204] For example, in S220, vector velocity can be calculated based on vector blood flow imaging technology. This solves the problem of non-laminar flow velocity measurement, thereby accurately obtaining the velocity component of the vector velocity of blood flow at each point through the cross-section along the normal direction of the cross-section during blood flow measurement, and also accurately obtaining the velocity component of the vector velocity of blood flow at each point parallel to the blood vessel wall.

[0205] One implementation method is to calculate the vector velocity using a multi-angle deflection emission approach, see [link to relevant documentation]. Figure 11 S220 may include S201 to S204.

[0206] S201, emitting a first ultrasound beam toward a target area, including blood vessels, in at least two directions;

[0207] S202, receiving the ultrasonic echo of the first ultrasonic beam returning from the target area to obtain ultrasonic echo signals along each of the at least two directions;

[0208] S203, Based on the ultrasound echo signals along each of the at least two directions, determine the velocity component of the blood flow velocity in the blood vessel along each of the at least two directions;

[0209] S204, determine the vector velocity of blood flow in the blood vessel based on the velocity components in each of the at least two directions;

[0210] S210, determine the position of the measurement point on the blood vessel wall in each frame;

[0211] S230, determine the shear stress or shear rate of the blood vessel wall based on the position of the measurement point in each frame and the vector velocity.

[0212] For example, at least two directions may include a first direction and a second direction, which have different deflection angles. For instance, the first direction is parallel to the normal direction of the array element arrangement, and the second direction forms an acute angle with the normal direction of the array element arrangement. By controlling the transmission delay of each array element, ultrasonic beams with different deflection angles can be obtained. Based on the ultrasonic echo signals obtained from the ultrasonic beams with different deflection angles, the velocity components of the blood flow corresponding to different deflection angles can be obtained, and the vector velocity of the blood flow can be obtained based on the velocity components at different deflection angles. For details on how to obtain the vector velocity of the blood flow, please refer to the foregoing. Figure 3 The relevant descriptions of the embodiments will not be repeated here.

[0213] As another implementation method, the vector velocity can be calculated based on the speckle tracking method, the transverse wave oscillation method, or the multi-angle deflection receiver method. See [link to relevant documentation]. Figure 12 S220 may include S205 to S207.

[0214] S205, emit a first ultrasound beam toward a target area, which includes blood vessels;

[0215] S206, Receive the ultrasonic echo of the first ultrasonic beam returning from the target area to obtain the ultrasonic echo signal;

[0216] S207, determine the vector velocity of blood flow in blood vessels based on ultrasound echo signals;

[0217] S210, determine the position of the measurement point on the blood vessel wall in each frame;

[0218] S230, determine the shear stress or shear rate of the blood vessel wall based on the position of the measurement point in each frame and the vector velocity.

[0219] For example, S207 may include: tracking the ultrasound echo signal using a speckle tracking method to obtain the vector velocity of blood flow in the blood vessel. Alternatively, S207 may include: determining the transverse and longitudinal velocities of blood flow in the blood vessel based on the ultrasound echo signal, and obtaining the vector velocity of blood flow in the blood vessel based on the transverse and longitudinal velocities. Alternatively, S206 may include: receiving ultrasound echoes from a first ultrasound beam returning from a target area along at least two directions to obtain ultrasound echo signals along each of the at least two directions; correspondingly, S207 may include: determining the velocity component of blood flow in the blood vessel along each of the at least two directions based on the ultrasound echo signals in each of the at least two directions; and determining the vector velocity of blood flow in the blood vessel based on the velocity components in each of the at least two directions. For details on how to obtain the vector velocity of blood flow, please refer to the foregoing. Figure 4 The relevant descriptions of the embodiments will not be repeated here.

[0220] In addition, it should be noted that, although Figure 10 The process of determining the vector velocity, S220, is shown to be executed after S210. Figure 11 The process of determining the vector velocity, S201 to S204, is shown to be executed before S210. Figure 12 The process of determining the vector velocity, S205 to S207, is shown to be executed before S210. However, the specific order of the two processes, S210 and S220, is not limited in this embodiment of the invention.

[0221] Considering that the diameter of a blood vessel is not a constant value but changes with the phases of the cardiac cycle, the position of the vessel wall also changes over time. In this embodiment of the invention, the position of the measurement point on the vessel wall at each moment can be determined in S210, where each moment can be represented as a frame.

[0222] It is understood that embodiments of the present invention may further include: transmitting a second ultrasonic beam toward a target area and receiving the ultrasonic echo of the second ultrasonic beam returning from the target area to obtain an ultrasonic echo signal; processing the ultrasonic echo signal to obtain an ultrasonic image of the target area. The processing may include beamforming, orthogonal demodulation, filtering, etc.

[0223] Optionally, it may also include: displaying ultrasound images of blood vessels and representing hemodynamic parameters in the ultrasound images.

[0224] In one implementation, S210 may include: obtaining multiple ultrasound images of the blood vessel based on the ultrasound echo signal corresponding to the first ultrasound beam; and determining the position of the measurement point on the blood vessel wall in each frame based on each frame of the multiple ultrasound images. Alternatively, S210 may include: transmitting a fourth ultrasound beam to a target area; receiving the ultrasound echo of the fourth ultrasound beam returning from the target area to obtain an ultrasound echo signal; obtaining multiple ultrasound images of the blood vessel based on the ultrasound echo signal corresponding to the fourth ultrasound beam; and determining the position of the measurement point on the blood vessel wall in each frame based on each frame of the multiple ultrasound images.

[0225] The multi-frame ultrasound images of blood vessels can be multi-frame longitudinal section ultrasound images of blood vessels. The longitudinal section ultrasound images of blood vessels are acquired, and these longitudinal section ultrasound images can be two-dimensional grayscale images.

[0226] Optionally, determining the position of the measurement point on the blood vessel wall in each frame may include: using a tracking algorithm to determine the position of the measurement point on the blood vessel wall in each frame. Alternatively, the position of the measurement point marked by the user on each frame of ultrasound image may be obtained to determine the position of the measurement point on the blood vessel wall in each frame.

[0227] Specifically, users can mark measurement points on the ultrasound image of the initial frame, such as... Figure 13 As shown. Following this, a tracking algorithm can be used to determine the position of the measurement point in each frame, considering the relative positional relationship between the vessel walls in each adjacent pair of ultrasound images.

[0228] Optionally, determining the position of the measurement points on the blood vessel wall in each frame may include: performing image recognition on the ultrasound image to determine the blood vessel wall, and then determining the position of each point on the blood vessel wall in each frame.

[0229] This invention also provides a method for determining hemodynamic parameters, which may include vessel wall shear stress or vessel wall shear rate, such as... Figure 14 As shown, the method includes:

[0230] S240, emits an ultrasound beam toward a target area, which includes blood vessels;

[0231] S250, receive the ultrasonic echo of the ultrasonic beam returning from the target area to obtain an ultrasonic echo signal;

[0232] S260, determine the diameter of the cross-section of the blood vessel corresponding to the measurement point on the blood vessel wall in each frame;

[0233] S270, Based on the ultrasound echo signal, determine the maximum velocity value of blood flow at the measurement point on the diameter of the cross-section of the blood vessel corresponding to each frame;

[0234] S280, determine the shear stress or shear rate of the blood vessel wall based on the diameter of the cross-section of the blood vessel corresponding to the measurement point in each frame and the maximum velocity value.

[0235] In this embodiment of the invention, the position of the measurement point p in each frame can be represented as p(x,y,t), where t represents the frame number and (x,y) represents the position.

[0236] When measuring WSS using traditional ultrasound methods such as PW, the formula used can be:

[0237]

[0238] Where μ represents the blood viscosity coefficient, d represents the blood vessel diameter, and v max This represents the maximum blood flow velocity across the diameter of the blood vessel, and v max It can be obtained through PW measurement. Considering that τ is actually an instantaneous value, that is, a WSS can be obtained based on each frame of the image, the formula for calculating the shear stress of the blood vessel wall can be expressed as:

[0239]

[0240] Among them, v max (t) varies with time, and the maximum blood flow velocity for each frame can be measured using the PW method. However, it should be noted that the diameter is a fixed value in the above equation, and its variation with time is not taken into account.

[0241] Figure 14 The variation of diameter over time is taken into account. As one implementation, S260 may include: obtaining the diameter of the blood vessel's cross-section for each frame at the measurement point based on the longitudinal section ultrasound image at the measurement point. For example, see the above-described combination. Figure 5The details described herein will not be repeated here. As another implementation, S260 may include: obtaining the diameter of the cross-section of the blood vessel corresponding to each frame at the measurement point based on the cross-sectional ultrasound image at the measurement point. For example, the cross-section at the measurement point can be determined, approximated as a circle, and then the diameter of the circle can be determined. The cross-section can be determined through image recognition, manually defined by the user, or a closed line drawn by several points on the blood vessel wall (as described above). Figure 7 (As mentioned above). The cross-section can be approximated as a circle using methods such as curve fitting. In this embodiment of the invention, the change in diameter over time can be expressed as d(t).

[0242] Accordingly, S280 can be calculated using the following formula, which can be obtained by further rewriting the above formula considering the change in diameter:

[0243]

[0244] This allows us to obtain the shear stress of the blood vessel wall in each frame, taking into account the change in diameter.

[0245] Accordingly, the formula for calculating the shear rate of the blood vessel wall can be expressed as:

[0246]

[0247] This allows us to obtain the shear rate of the blood vessel wall in each frame, taking into account changes in diameter.

[0248] However, the above calculation of τ or τ(t) is based on the laminar flow assumption. In the non-laminar flow case, WSS can be calculated according to the following formula:

[0249]

[0250] Where v represents the velocity component of the vector velocity along the tangent direction to the blood vessel wall, which is parallel to the blood vessel wall when the blood vessel wall is straight; in non-laminar flow conditions, it can be obtained through vector velocity, such as... Figure 15 As shown. Here, 'wall' indicates the location on the vessel wall where the calculated WSS was measured, such as... Figure 15 The “WSS measurement point” is shown in the figure.

[0251] It should be noted that, although Figure 15 The blood vessel wall shown is a straight line, but in reality, the blood vessel wall is not necessarily a straight line. Accordingly, the direction of the velocity component of blood flow parallel to the blood vessel wall refers to the direction of the tangent to the measurement point of the blood vessel wall.

[0252] It should be understood that although the measurement point on the blood vessel wall is constant relative to the blood vessel wall, the blood vessel wall itself is changing; for example, the coordinates of the blood vessel wall change with different phases of the cardiac cycle. This embodiment of the invention fully considers the changes in the position of the blood vessel wall. Therefore, embodiment S230 of this invention may include: calculating the velocity component of the vector velocity of the blood flow near the measurement point along the tangent direction of the measurement point on the blood vessel wall; and obtaining the shear stress or shear rate of the blood vessel wall based on the position of the measurement point in each frame and the velocity component of the vector velocity of the blood flow near the measurement point along the tangent direction of the measurement point on the blood vessel wall.

[0253] Specifically, the shear stress or shear rate of the blood vessel wall can be calculated using the following formula:

[0254]

[0255] Where μ represents the blood viscosity coefficient, and v represents the velocity component in the tangential direction of the blood vessel wall. This represents the velocity derivative of the instantaneous vector velocity of blood flow near the measurement point along the tangent direction of the measurement point to the vessel wall. express The corresponding distance derivative, wall(t), represents the instantaneous position of the measurement point, and τ represents the shear stress of the blood vessel wall. This indicates the shear rate of the blood vessel wall.

[0256] Thus, through Figures 10 to 15 The illustrated embodiment allows for the acquisition of vessel wall shear stress or vessel wall shear rate. Specifically, it allows for the acquisition of vessel wall shear stress or vessel wall shear rate for each frame, i.e., the change of vessel wall shear stress or vessel wall shear rate at the measurement point over time. Alternatively, it allows for the acquisition of instantaneous vessel wall shear stress or vessel wall shear rate for a specific frame or several frames, such as the vessel wall shear stress or vessel wall shear rate at a specific moment in the cardiac cycle at the measurement point.

[0257] In this way, the shear stress or shear rate of the blood vessel wall at any time (frame) can be obtained. Optionally, the maximum value of WSS within a unit time (such as one cardiac cycle or one minute) can be obtained further.

[0258] In another implementation, following S230 or S280, at least one of the following may be calculated based on the vascular wall shear stress over a cardiac cycle or multiple frames over a period of time: oscillatory shear index (OSI), relative residence time (RRT), and time-averaged vascular wall shear stress (TAWSS). In other words, the hemodynamic parameters may also include one or more of OSI, RRT, and TAWSS.

[0259] OSI represents the degree of change in the direction of WSS within a time period (such as a cardiac cycle or one minute, denoted as T), and can be calculated using the following formula: Furthermore, the OSI value varies between 0 and 0.5. If the direction of the WSS does not change within the time interval T, the OSI value is 0. If the direction of the WSS changes, the OSI value is greater than 0, but cannot exceed 0.5.

[0260] Wherein, TAWSS is the time-averaged WSS over a period of time T, calculated using the following formula:

[0261] RRT can be calculated using the following formula:

[0262] Therefore, it can be seen that in calculating hemodynamic parameters such as vessel wall shear stress or vessel wall shear rate, the embodiments of the present invention take into account the changes in vessel wall position caused by changes in vessel diameter, thereby making the calculated vessel wall shear stress or vessel wall shear rate more accurate.

[0263] In another implementation, or further, the hemodynamic parameters may also include blood flow rate. Then, after S220 (or S204 or S207), it may also include: determining the function of the cross-sectional area of ​​the blood vessel changing over time; and determining the blood flow rate per unit time based on the function of the cross-sectional area changing over time and the vector velocity.

[0264] For example, determining the blood flow rate per unit time based on the function of cross-sectional area changing with time and the vector velocity may include: calculating the velocity component of the vector velocity along the normal direction of the cross-section of the blood vessel; and determining the blood flow rate per unit time based on the function of cross-sectional area changing with time and the velocity component of the vector velocity along the normal direction of the cross-section of the blood vessel.

[0265] Specifically, the process of calculating blood flow per unit time can be found in the aforementioned combination. Figures 2 to 4 The process described will not be repeated here.

[0266] Now return to Figure 1 The ultrasonic device 10 shown.

[0267] In one implementation, a transmit / receive selection switch 120 can excite an ultrasound probe 110 to transmit a first ultrasound beam toward a target region, including a blood vessel, via a transmitting circuit in at least two directions, and receive ultrasound echoes of the first ultrasound beam returning from the target region. A processor 140 can obtain ultrasound echo signals along each of the at least two directions based on the ultrasound echoes; determine the velocity components of the blood flow in the blood vessel along each of the at least two directions based on the ultrasound echo signals along each of the at least two directions; determine the vector velocity of the blood flow in the blood vessel based on the velocity components along each of the at least two directions; determine the function of time variation of the cross-sectional area of ​​the blood vessel; and determine the blood flow rate per unit time based on the function of time variation of the cross-sectional area and the vector velocity.

[0268] In another implementation, a transmit / receive selection switch 120 can excite an ultrasound probe 110 to transmit a first ultrasound beam toward a target area, including a blood vessel, via a transmitting circuit, and receive the ultrasound echo of the first ultrasound beam returning from the target area. A processor 140 can obtain an ultrasound echo signal based on this echo; determine the vector velocity of blood flow in the blood vessel based on the ultrasound echo signal; determine the function of change of the cross-sectional area of ​​the blood vessel over time; and determine the blood flow rate per unit time based on the function of change of the cross-sectional area over time and the vector velocity.

[0269] In another implementation, a transmit / receive selection switch 120 can excite an ultrasound probe 110 to transmit an ultrasound beam toward a target area, including a blood vessel, via a transmitting circuit, and receive the ultrasound echo of the ultrasound beam returning from the target area. A processor 140 can obtain an ultrasound echo signal based on this echo; determine, according to the ultrasound echo signal, the average velocity of blood flow at the sampling gate in the blood vessel along the normal direction of the blood vessel's cross-section; determine the function of change of the blood vessel's cross-sectional area over time; and determine the blood flow rate per unit time based on the function of change of the cross-sectional area over time and the average velocity of the blood flow.

[0270] In another implementation, a transmit / receive selection switch 120 can excite an ultrasound probe 110 to emit a first ultrasound beam toward a target region, including a blood vessel, via a transmitting circuit in at least two directions, and receive ultrasound echoes of the first ultrasound beam returning from the target region. A processor 140 can obtain ultrasound echo signals along each of the at least two directions based on the ultrasound echoes; determine the velocity components of the blood flow in the blood vessel along each of the at least two directions based on the ultrasound echo signals along each of the at least two directions; determine the vector velocity of the blood flow in the blood vessel based on the velocity components along each of the at least two directions; determine the position of a measurement point on the blood vessel wall in each frame; and determine the blood vessel wall shear stress or blood vessel wall shear rate based on the position of the measurement point in each frame and the vector velocity.

[0271] In another implementation, the transmit / receive selection switch 120 can excite the ultrasound probe 110 to transmit a first ultrasound beam to a target area, including a blood vessel, via a transmitting circuit, and receive the ultrasound echo of the first ultrasound beam returning from the target area. The processor 140 can obtain an ultrasound echo signal based on this echo; determine the vector velocity of blood flow in the blood vessel based on the ultrasound echo signal; determine the position of a measurement point on the blood vessel wall in each frame; and determine the blood vessel wall shear stress or blood vessel wall shear rate based on the position of the measurement point in each frame and the vector velocity.

[0272] In another implementation, the transmit / receive selection switch 120 can excite the ultrasound probe 110 to transmit an ultrasound beam to a target area, including a blood vessel, via a transmitting circuit, and receive the ultrasound echo of the ultrasound beam returning from the target area. The processor 140 can obtain an ultrasound echo signal based on this echo; determine the diameter of the cross-section of the blood vessel corresponding to the measurement point on the blood vessel wall in each frame; determine the maximum blood flow velocity value at the diameter of the cross-section of the blood vessel corresponding to the measurement point in each frame based on the ultrasound echo signal; and determine the blood vessel wall shear stress or blood vessel wall shear rate based on the diameter of the cross-section of the blood vessel corresponding to the measurement point in each frame and the maximum velocity value.

[0273] Exemplarily, the system may further include: a transmit / receive selection switch 120 that can excite the ultrasound probe 110 to transmit a second ultrasound beam toward a target area via a transmitting circuit, and receive the ultrasound echo of the second ultrasound beam returning from the target area. A processor 140 can obtain a second ultrasound echo signal based on the ultrasound echo of the second ultrasound beam; process the second ultrasound echo signal to obtain an ultrasound image of the blood vessel. A display 150 can display the ultrasound image of the blood vessel. Optionally, hemodynamic parameters may be further displayed in the displayed ultrasound image. These hemodynamic parameters include, but are not limited to, blood flow, vessel wall shear stress, or vessel wall shear rate.

[0274] In addition, embodiments of the present invention also provide a computer storage medium on which a computer program is stored. When the computer program is executed by a computer or processor, the aforementioned functions can be implemented. Figures 2 to 4 , Figures 9 to 12 and Figure 14 The steps of the method for determining hemodynamic parameters shown in any of the examples. For example, the computer storage medium is a computer-readable storage medium.

[0275] In one embodiment, the computer program instructions, when executed by a computer or processor, cause the computer or processor to perform the following steps: emitting a first ultrasonic beam toward a target region, the target region including a blood vessel, along at least two directions; receiving ultrasonic echoes of the first ultrasonic beam returning from the target region to obtain ultrasonic echo signals along each of the at least two directions; determining, based on the ultrasonic echo signals along each of the at least two directions, the velocity component of the blood flow in the blood vessel along each of the at least two directions; determining, based on the velocity component of the blood flow in each of the at least two directions, the vector velocity of the blood flow in the blood vessel; determining a function of the cross-sectional area of ​​the blood vessel changing over time; and determining the blood flow rate per unit time based on the function of the cross-sectional area changing over time and the vector velocity.

[0276] In one embodiment, the computer program instructions, when executed by a computer or processor, cause the computer or processor to perform the following steps: emitting a first ultrasonic beam toward a target area, the target area including a blood vessel; receiving ultrasonic echoes of the first ultrasonic beam returning from the target area to obtain an ultrasonic echo signal; determining the vector velocity of blood flow in the blood vessel based on the ultrasonic echo signal; determining a function of the change of the cross-sectional area of ​​the blood vessel over time; and determining the blood flow rate per unit time based on the function of the change of the cross-sectional area over time and the vector velocity.

[0277] In one embodiment, the computer program instructions, when executed by a computer or processor, cause the computer or processor to perform the following steps: emitting an ultrasonic beam toward a target area, the target area including a blood vessel; receiving ultrasonic echoes of the ultrasonic beam returning from the target area to obtain an ultrasonic echo signal; determining, based on the ultrasonic echo signal, the average velocity of blood flow at a sampling gate in the blood vessel along the normal direction of the cross-section of the blood vessel; determining a function of the change in the cross-sectional area of ​​the blood vessel over time; and determining the blood flow rate per unit time based on the function of the change in the cross-sectional area over time and the average velocity of the blood flow.

[0278] In another embodiment, the computer program instructions, when executed by a computer or processor, cause the computer or processor to perform the following steps: emitting a first ultrasonic beam toward a target region, including a blood vessel, along at least two directions; receiving ultrasonic echoes of the first ultrasonic beam returning from the target region to obtain ultrasonic echo signals along each of the at least two directions; determining, based on the ultrasonic echo signals along each of the at least two directions, the velocity component of the blood flow in the blood vessel along each of the at least two directions; determining, based on the velocity component of the blood flow in each of the at least two directions, the vector velocity of the blood flow in the blood vessel; determining the position of a measurement point on the blood vessel wall in each frame; and determining the blood vessel wall shear stress or blood vessel wall shear rate based on the position of the measurement point in each frame and the vector velocity.

[0279] In one embodiment, the computer program instructions, when executed by a computer or processor, cause the computer or processor to perform the following steps: emitting a first ultrasound beam toward a target area, the target area including a blood vessel; receiving ultrasound echoes of the first ultrasound beam returning from the target area to obtain an ultrasound echo signal; determining the vector velocity of blood flow in the blood vessel based on the ultrasound echo signal; determining the position of a measurement point on the blood vessel wall in each frame; and determining the shear stress or shear rate of the blood vessel wall based on the position of the measurement point in each frame and the vector velocity.

[0280] In one embodiment, the computer program instructions, when executed by a computer or processor, cause the computer or processor to perform the following steps: emitting an ultrasonic beam toward a target area, the target area including a blood vessel; receiving ultrasonic echoes of the ultrasonic beam returning from the target area to obtain an ultrasonic echo signal; determining the diameter of the cross-section of the blood vessel corresponding to a measurement point on the blood vessel wall in each frame; determining, based on the ultrasonic echo signal, a maximum velocity value of blood flow at the diameter of the cross-section of the blood vessel corresponding to the measurement point in each frame; and determining the blood vessel wall shear stress or blood vessel wall shear rate based on the diameter of the cross-section of the blood vessel corresponding to the measurement point in each frame and the maximum velocity value.

[0281] Computer storage media may include, for example, a memory card for a smartphone, a storage component for a tablet computer, a hard disk for a personal computer, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a portable compact disc read-only memory (CD-ROM), a USB storage device, or any combination of the above storage media. A computer-readable storage medium may be any combination of one or more computer-readable storage media.

[0282] In addition, embodiments of the present invention also provide a computer program product comprising instructions that, when executed by a computer, cause the computer to perform the aforementioned... Figures 2 to 4 , Figures 9 to 12 and Figure 14 The steps of any of the methods shown in the figure for determining hemodynamic parameters.

[0283] Therefore, in calculating hemodynamic parameters such as blood flow and vessel wall shear stress or vessel wall shear rate, the embodiments of the present invention take into account the changes in vessel cross-sectional area and vessel wall position caused by changes in vessel diameter, thereby making the calculated hemodynamic parameters such as blood flow and vessel wall shear stress or vessel wall shear rate more accurate.

[0284] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of the invention. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of the invention. All such changes and modifications are intended to be included within the scope of the invention as claimed in the appended claims.

[0285] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0286] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed.

[0287] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0288] Similarly, it should be understood that, in order to streamline the invention and aid in understanding one or more of the various aspects of the invention, features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof in the description of exemplary embodiments of the invention. However, this approach should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the corresponding claims, its inventive point lies in solving the corresponding technical problem with fewer features than all of those in a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0289] Those skilled in the art will understand that, apart from the mutual exclusion of features, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or apparatus so disclosed can be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0290] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0291] The various component embodiments of the present invention can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will understand that microprocessors or digital signal processors (DSPs) can be used in practice to implement some or all of the functions of some modules in the article analysis device according to embodiments of the present invention. The present invention can also be implemented as an apparatus program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such programs implementing the present invention can be stored on a computer-readable medium or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

[0292] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

[0293] The above description is merely a specific embodiment of the present invention or an explanation of that embodiment. The scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for determining hemodynamic parameters, characterized in that, The hemodynamic parameters include blood flow rate, and the method includes: A first ultrasound beam is emitted toward a target area, including blood vessels, in at least two directions; Receive the ultrasonic echo of the first ultrasonic beam returning from the target area to obtain ultrasonic echo signals along each of the at least two directions; Based on the ultrasound echo signals along each of the at least two directions, determine the velocity component of the blood flow in the blood vessel along each of the at least two directions; The vector velocity of blood flow in the blood vessel is determined based on the velocity components in each of the at least two directions; Determine the function of how the cross-sectional area of ​​the blood vessel changes over time; The blood flow rate per unit time is determined based on the function of cross-sectional area change over time and the vector velocity; The step of determining the blood flow rate per unit time based on the time-varying function of the cross-sectional area and the vector velocity includes: Calculate the velocity component of the vector velocity along the normal direction of the cross-section of the blood vessel; The blood flow rate per unit time is determined based on the function of the cross-sectional area changing with time and the velocity component of the vector velocity along the normal direction of the cross-section of the blood vessel.

2. A method for determining hemodynamic parameters, characterized in that, The hemodynamic parameters include blood flow rate, and the method includes: A first ultrasound beam is emitted toward a target area, said target area including blood vessels; Receive the ultrasonic echo of the first ultrasonic beam returning from the target area to obtain an ultrasonic echo signal; The vector velocity of blood flow in the blood vessel is determined based on the ultrasound echo signal. Determine the function of how the cross-sectional area of ​​the blood vessel changes over time; The blood flow rate per unit time is determined based on the function of cross-sectional area change over time and the vector velocity; The step of determining the blood flow rate per unit time based on the time-varying function of the cross-sectional area and the vector velocity includes: Calculate the velocity component of the vector velocity along the normal direction of the cross-section of the blood vessel; The blood flow rate per unit time is determined based on the function of the cross-sectional area changing with time and the velocity component of the vector velocity along the normal direction of the cross-section of the blood vessel.

3. The method according to claim 1 or 2, characterized in that, The target region includes the cross-section of the blood vessel. Determining the function of the change in the cross-sectional area of ​​the blood vessel over time includes: A second ultrasonic beam is emitted toward the target area; Receive the ultrasonic echo of the second ultrasonic beam returning from the target area to obtain an ultrasonic echo signal; Based on the ultrasound echo signal corresponding to the second ultrasound beam, a multi-frame cross-sectional ultrasound image of the blood vessel is obtained; Based on each frame of the multi-frame cross-sectional ultrasound images, the selected location of the blood vessel is determined to be within the cross-sectional area corresponding to each frame.

4. The method according to claim 1 or 2, characterized in that, The target region includes the cross-section of the blood vessel. Determining the function of the change in the cross-sectional area of ​​the blood vessel over time includes: Based on the ultrasound echo signal corresponding to the first ultrasound beam, a multi-frame cross-sectional ultrasound image of the blood vessel is obtained; Based on each frame of the multi-frame cross-sectional ultrasound images, the selected location of the blood vessel is determined to be within the cross-sectional area corresponding to each frame.

5. The method according to claim 3, characterized in that, Determining the selected location of the blood vessel within the corresponding cross-sectional area of ​​each frame includes: For each frame of cross-sectional ultrasound image: Identify multiple blood vessel wall pixels in the cross-sectional ultrasound image; Construct a closed line based on some or all of the blood vessel wall pixels among the plurality of blood vessel wall pixels; The area of ​​the space enclosed by the closed line is defined as the cross-sectional area.

6. The method according to claim 5, characterized in that, Determining multiple blood vessel wall pixels in the cross-sectional ultrasound image includes: If the difference between the signal value of a certain pixel and the signal values ​​of several surrounding pixels of that pixel meets a preset condition, then that pixel is identified as a blood vessel wall pixel.

7. The method according to claim 6, characterized in that, The preset conditions include: Among the several differences obtained by subtracting the signal value of a certain pixel from the signal values ​​of several surrounding pixels, the ratio of the number of differences greater than a preset difference to the number of surrounding pixels is greater than a threshold.

8. The method according to any one of claims 5 to 7, characterized in that, The step of constructing a closed line based on some or all of the multiple blood vessel wall pixels includes: The closed line is constructed by connecting some or all of the multiple blood vessel wall pixels using curve fitting or by using a polyline.

9. The method according to claim 4, characterized in that, Determining the selected location of the blood vessel within the corresponding cross-sectional area of ​​each frame includes: The selected location of the blood vessel is determined by image recognition within the corresponding cross-sectional area of ​​each frame, or... Obtain the cross-sectional area of ​​the selected location of the blood vessel, as measured by the user, in each frame.

10. The method according to claim 1 or 2, characterized in that, The target region includes the longitudinal section of the blood vessel. The determination of the function of the change of the cross-sectional area of ​​the blood vessel over time includes: A third ultrasonic beam is emitted toward the target area; Receive the ultrasonic echo of the third ultrasonic beam returning from the target area to obtain an ultrasonic echo signal; Based on the ultrasound echo signal corresponding to the third ultrasound beam, a multi-frame longitudinal section ultrasound image of the blood vessel is obtained; Based on each frame of the multi-frame longitudinal section ultrasound image, the diameter of the selected location of the blood vessel in each frame is determined. Based on the diameter, the selected location of the blood vessel is determined to be within the corresponding cross-sectional area of ​​each frame.

11. The method according to claim 1 or 2, characterized in that, The target region includes the longitudinal section of the blood vessel. The determination of the function of the change of the cross-sectional area of ​​the blood vessel over time includes: Based on the ultrasound echo signal corresponding to the first ultrasound beam, a multi-frame longitudinal section ultrasound image of the blood vessel is obtained; Based on each frame of the multi-frame longitudinal section ultrasound image, the diameter of the selected location of the blood vessel in each frame is determined. Based on the diameter, the selected location of the blood vessel is determined to be within the corresponding cross-sectional area of ​​each frame.

12. The method according to claim 10, characterized in that, Determining the selected location of the blood vessel in the diameter corresponding to each frame includes: The selected location of the blood vessel is determined by image recognition, corresponding to the diameter in each frame, or... Obtain the diameter of the selected location of the blood vessel, as measured by the user, in each frame.

13. The method according to claim 1 or 2, characterized in that, The hemodynamic parameters also include vessel wall shear stress or vessel wall shear rate, and the method further includes: Determine the average diameter of the blood vessel within the unit time period; The average value of the blood flow rate and the average value of the diameter within the unit time is determined.

14. The method according to claim 1 or 2, characterized in that, The hemodynamic parameters also include vessel wall shear stress or vessel wall shear rate, and the method further includes: Determine the position of the measurement points on the blood vessel wall in each frame; The vessel wall shear stress or vessel wall shear rate is determined based on the position of the measurement point in each frame and the vector velocity.

15. The method according to claim 14, characterized in that, Determining the vessel wall shear stress or vessel wall shear rate based on the position of the measurement point in each frame and the vector velocity includes: Determine the velocity component of the vector velocity of blood flow near the measurement point along the tangential direction of the measurement point on the vessel wall; Based on the position of the measurement point in each frame and the velocity component of the blood flow vector velocity near the measurement point along the tangential direction of the measurement point on the vessel wall, the shear stress or shear rate of the vessel wall is determined.

16. The method according to claim 2, characterized in that, Determining the vector velocity of blood flow in the blood vessel based on the ultrasound echo signal includes: The ultrasound echo signal is tracked using a speckle tracking method to obtain the vector velocity of blood flow in the blood vessel; or, Based on the ultrasound echo signal, the lateral and longitudinal velocities of the blood flow in the blood vessel are determined, and the vector velocity of the blood flow in the blood vessel is obtained based on the lateral and longitudinal velocities of the blood flow.

17. The method according to claim 2, characterized in that, Receiving the ultrasonic echo of the first ultrasonic beam returning from the target area to obtain an ultrasonic echo signal includes: The ultrasonic echoes of the first ultrasonic beam returning from the target area are received in at least two directions to obtain ultrasonic echo signals in each of the at least two directions. Determining the vector velocity of blood flow in the blood vessel based on the ultrasound echo signal includes: Based on the ultrasound echo signals in each of the at least two directions, determine the velocity component of the blood flow in the blood vessel along each of the at least two directions; The vector velocity of blood flow in the blood vessel is determined based on the velocity component in each of the at least two directions.

18. A method for determining hemodynamic parameters, characterized in that, The hemodynamic parameters include blood flow rate, and the method includes: An ultrasonic beam is emitted toward a target area, which includes blood vessels; Receive the ultrasonic echo of the ultrasonic beam returning from the target area to obtain an ultrasonic echo signal; Based on the ultrasound echo signal, determine the average velocity of the blood flow at the sampling gate in the blood vessel along the normal direction of the cross-section of the blood vessel. Determine the function of how the cross-sectional area of ​​the blood vessel changes over time; The blood flow rate per unit time is determined based on the function of the cross-sectional area changing over time and the average velocity of the blood flow.

19. An ultrasonic device, characterized in that, include: Ultrasonic probe; A transmit / receive selection switch is used to excite the ultrasound probe to emit a first ultrasound beam toward a target area, including blood vessels, via a transmit circuit in at least two directions, and to receive the ultrasound echo of the first ultrasound beam returning from the target area. Memory is used to store programs executed by the processor; The processor is used for: Based on the ultrasonic echo, ultrasonic echo signals are obtained along each of the at least two directions; Based on the ultrasound echo signals along each of the at least two directions, determine the velocity component of the blood flow in the blood vessel along each of the at least two directions; The vector velocity of blood flow in the blood vessel is determined based on the velocity components in each of the at least two directions; Determine the function of how the cross-sectional area of ​​the blood vessel changes over time; The blood flow rate per unit time is determined based on the function of cross-sectional area change over time and the vector velocity; The step of determining the blood flow rate per unit time based on the time-varying function of the cross-sectional area and the vector velocity includes: Calculate the velocity component of the vector velocity along the normal direction of the cross-section of the blood vessel; The blood flow rate per unit time is determined based on the function of the cross-sectional area changing with time and the velocity component of the vector velocity along the normal direction of the cross-section of the blood vessel.

20. An ultrasonic device, characterized in that, include: Ultrasonic probe; A transmit / receive selection switch is used to excite the ultrasound probe to emit an ultrasound beam toward a target area via a transmit circuit, and to receive the ultrasound echo of the ultrasound beam returning from the target area, the target area including blood vessels; Memory is used to store programs executed by the processor; The processor is used for: The ultrasonic echo signal is obtained based on the ultrasonic echo; Based on the ultrasound echo signal, determine the average velocity of the blood flow at the sampling gate in the blood vessel along the normal direction of the cross-section of the blood vessel. Determine the function of how the cross-sectional area of ​​the blood vessel changes over time; The blood flow rate per unit time is determined based on the function of the cross-sectional area changing over time and the average velocity of the blood flow.

21. A computer storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a computer or processor, it implements the steps of the method according to any one of claims 1 to 18.

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