CN115670511A

CN115670511A - Blood flow measuring method based on ultrasound and ultrasonic imaging system

Info

Publication number: CN115670511A
Application number: CN202110838081.2A
Authority: CN
Inventors: 王勃; 刘德杰
Original assignee: Shenzhen Mindray Bio Medical Electronics Co Ltd
Current assignee: Shenzhen Mindray Bio Medical Electronics Co Ltd
Priority date: 2021-07-23
Filing date: 2021-07-23
Publication date: 2023-02-03

Abstract

An ultrasound-based blood flow measurement method and an ultrasound imaging system, the method comprising: controlling an ultrasonic probe to emit first ultrasonic waves to a target area containing a heart valve and receiving echoes of the first ultrasonic waves returned by the target area to obtain first ultrasonic echo signals; performing signal processing on the first ultrasonic echo signal to obtain blood flow velocity information of a target area; determining constant velocity information according to the blood flow velocity information; determining a constant-speed convergence surface which meets the preset requirement in the matching degree with the hemisphere or the semicircle according to the constant-speed information; determining a first measurement parameter according to the isokinetic convergence surface, wherein the first measurement parameter comprises an aliasing velocity and a blood flow radius, the aliasing velocity is obtained according to the blood flow velocity corresponding to the isokinetic convergence surface, and the blood flow radius is obtained according to the radius of the hemispherical or semicircular isokinetic convergence surface; and controlling the display to display the first measurement parameter. The scheme can automatically realize blood flow quantification analysis based on a near-end constant-speed surface area method.

Description

Blood flow measuring method based on ultrasound and ultrasonic imaging system

Technical Field

The present application relates to the field of ultrasound imaging technology, and more particularly, to an ultrasound-based blood flow measurement method and an ultrasound imaging system.

Background

With the increasing trend of aging of the population, the valve heart disease becomes a high-incidence cardiovascular disease. Valvular blood flow abnormalities are common clinical manifestations of valvular disease and impaired cardiac function, providing important diagnostic information. The echocardiogram is a preferred image evaluation method for valve hemodynamics evaluation, and is particularly important for preoperative evaluation, intraoperative monitoring and postoperative evaluation of valve regurgitation. The american echocardiography Association (ASE) first issued guidelines for the assessment of valve regurgitation in 2003. In 2017, the ASE updates a reflux evaluation guide, and further standardizes a quantitative evaluation method for reflux. The domestic experts also introduced the consensus of Chinese experts in the ultrasonic cardiogram evaluation of mitral valve regurgitation interventional therapy in 2019. Although expert consensus provides a simplified evaluation procedure, a complete evaluation in accordance with international guidelines is necessary for cases where reflux is severe and intervention is considered, and the procedure is very complex.

At present, no intelligent workflow and a sound automatic analysis tool aiming at the abnormal valve blood flow problems such as valve regurgitation exist in the industry. Particularly, no automatic tool exists in the industry for the quantitative calculation which is important for diagnosis and treatment decision but is more complex. The proximal isovelocity surface area method (PISA) is a widely used method in the clinic to assess mitral valve, tricuspid regurgitation and valvular stenosis. At present, no automatic scheme related to the PISA method exists in the industry, measurement needs to be completed manually by depending on doctor experience, the difference between operators is large, and the inspection efficiency is low. With the popularization of the standardized assessment of valvular disease diagnosis and treatment, the problem is urgently solved.

Disclosure of Invention

A series of concepts in a simplified form are introduced in the summary section, which is described in further detail in the detailed description section. The summary of the invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In one aspect, an embodiment of the present invention provides an ultrasound-based blood flow measurement method, which is used in an ultrasound imaging system including an ultrasound probe, a processor, and a display, and includes: controlling the ultrasonic probe to emit first ultrasonic waves to a target area containing a heart valve and receive echoes of the first ultrasonic waves returned by the target area to obtain a first ultrasonic echo signal; the processor performs signal processing on the first ultrasonic echo signal to obtain blood flow velocity information of the target area; the processor determines isokinetic information according to the blood flow velocity information; the processor fits the constant speed information and determines a constant speed convergence surface of which the matching degree with the hemisphere or the semicircle meets the preset requirement according to the fitting result; the processor determines a first measurement parameter according to the isokinetic convergence surface, wherein the first measurement parameter comprises an aliasing velocity and a blood flow radius, the aliasing velocity is obtained according to the blood flow velocity corresponding to the isokinetic convergence surface, and the blood flow radius is obtained according to the radius of the hemispherical or semicircular isokinetic convergence surface; the processor controls the display to display the first measurement parameter.

In another aspect, an embodiment of the present invention provides an ultrasound-based blood flow measurement method, which is used in an ultrasound imaging system, where the ultrasound imaging system includes an ultrasound probe, a processor, and a display, and the method includes: controlling the ultrasonic probe to emit first ultrasonic waves to a target area containing a heart valve and receiving echoes of the first ultrasonic waves returned by the target area to obtain first ultrasonic echo signals; the processor performs signal processing on the first ultrasonic echo signal to obtain blood flow velocity information of the target area; the processor determines isokinetic information according to the blood flow velocity information; the processor determines a constant-speed converging surface which meets the preset requirement on the matching degree with the hemisphere or the semicircle according to the constant-speed information; the processor determines a first measurement parameter according to the isokinetic convergence surface, wherein the first measurement parameter comprises an aliasing velocity and a blood flow radius, the aliasing velocity is obtained according to the blood flow velocity corresponding to the isokinetic convergence surface, and the blood flow radius is obtained according to the radius of the hemispherical or semicircular isokinetic convergence surface; the processor controls the display to display the first measurement parameter.

Another aspect of an embodiment of the present invention provides an ultrasound imaging system, which includes an ultrasound probe, a transmitting circuit, a receiving circuit, a processor, and a display, wherein: the transmitting circuit is used for controlling the ultrasonic probe to transmit ultrasonic waves to a target area containing a heart valve; the receiving circuit is used for controlling the ultrasonic probe to receive the echo of the ultrasonic wave returned by the target area so as to obtain an ultrasonic echo signal; the processor is used for carrying out ultrasonic imaging based on the ultrasonic echo signal; the processor is further configured to perform the ultrasound-based blood flow measurement method as described above; the display is used for displaying the data output by the processor.

The blood flow measuring method based on the ultrasound and the ultrasonic imaging system can automatically realize abnormal blood flow analysis by the PISA method.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings may be obtained according to the drawings without inventive labor.

In the drawings:

FIG. 1 shows a schematic block diagram of an ultrasound imaging system according to an embodiment of the present application;

FIG. 2 shows a schematic flow diagram of an ultrasound-based blood flow measurement method according to an embodiment of the present application;

FIG. 3 shows a schematic diagram of a PISA method for blood flow measurement according to an embodiment of the application;

FIG. 4A shows a schematic view of a color flow image according to an embodiment of the present application;

figure 4B shows a schematic diagram of a doppler spectrum according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, exemplary embodiments according to the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the described embodiments are only some embodiments of the present application and not all embodiments of the present application, and that the present application is not limited by the example embodiments described herein. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the application described in the application without inventive step, shall fall within the scope of protection of the application.

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present application. It will be apparent, however, to one skilled in the art, that the present application may be practiced without one or more of these specific details. In other instances, well-known features of the art have not been described in order to avoid obscuring the present application.

It is to be understood that the present application is capable of implementation in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

In order to provide a thorough understanding of the present application, a detailed structure will be presented in the following description in order to explain the technical solutions presented in the present application. Alternative embodiments of the present application are described in detail below, however, the present application may have other implementations in addition to these detailed descriptions.

Next, an ultrasound imaging system according to an embodiment of the present application is first described with reference to fig. 1, and fig. 1 shows a schematic structural block diagram of an ultrasound imaging system 100 according to an embodiment of the present application.

As shown in fig. 1, the ultrasound imaging system 100 includes an ultrasound probe 110, transmit circuitry 112, receive circuitry 114, a processor 116, and a display 118. Further, the ultrasound imaging system may further include a transmit/receive selection switch 120 and a beam forming module 122, and the transmit circuit 112 and the receive circuit 114 may be connected to the ultrasound probe 110 through the transmit/receive selection switch 120.

The ultrasound probe 110 includes a plurality of transducer elements, which may be arranged in a line to form a linear array, or in a two-dimensional matrix to form an area array, or in a convex array. The transducer elements are used for transmitting ultrasonic waves according to the excitation electric signals or converting the received ultrasonic waves into the electric signals, so that each transducer element can be used for realizing the mutual conversion of the electric pulse signals and the ultrasonic waves, thereby realizing the transmission of the ultrasonic waves to tissues of a target area of a measured object and also receiving ultrasonic wave echoes reflected by the tissues. When ultrasonic detection is carried out, which transducer elements are used for transmitting ultrasonic waves and which transducer elements are used for receiving the ultrasonic waves can be controlled through a transmitting sequence and a receiving sequence, or the transducer elements are controlled to be time-slotted for transmitting the ultrasonic waves or receiving echoes of the ultrasonic waves. The transducer elements participating in the ultrasonic wave transmission can be simultaneously excited by the electric signals, so that the ultrasonic waves are transmitted simultaneously; alternatively, the transducer elements participating in the ultrasound beam transmission may be excited by several electrical signals with a certain time interval, so as to continuously transmit ultrasound waves with a certain time interval.

During ultrasound imaging, the transmit circuit 112 sends delay-focused transmit pulses through the transmit/receive selector switch 120 to the ultrasound probe 110. The ultrasonic probe 110 is excited by the transmission pulse to transmit an ultrasonic beam to a tissue in a target region of a measured object, receives an ultrasonic echo with tissue information reflected from the tissue in the target region after a certain time delay, and converts the ultrasonic echo back into an electrical signal again. The receiving circuit 114 receives the electrical signals generated by the ultrasound probe 110, obtains ultrasound echo signals, and sends the ultrasound echo signals to the beam forming module 122, and the beam forming module 122 performs processing such as focusing delay, weighting, and channel summation on the ultrasound echo data, and then sends the ultrasound echo data to the processor 116. The processor 116 performs signal detection, signal enhancement, data conversion, logarithmic compression, and the like on the ultrasonic echo signals to form an ultrasonic image. The ultrasound images obtained by the processor 116 may be displayed on the display 118 or may be stored in the memory 124.

Alternatively, the processor 116 may be implemented as software, hardware, firmware, or any combination thereof, and may use a single or multiple Application Specific Integrated Circuits (ASICs), a single or multiple general purpose Integrated circuits, a single or multiple microprocessors, a single or multiple programmable logic devices, or any combination of the foregoing, or other suitable circuits or devices. Also, the processor 116 may control other components in the ultrasound imaging system 100 to perform the respective steps of the methods in the various embodiments herein.

The display 118 is connected with the processor 116, and the display 118 may be a touch display screen, a liquid crystal display screen, or the like; alternatively, the display 118 may be a separate display such as a liquid crystal display, a television, or the like, which is separate from the ultrasound imaging system 100; alternatively, the display 118 may be a display screen of an electronic device such as a smartphone, tablet, etc. The number of the display 118 may be one or more.

The display 118 can display the ultrasound image obtained by the processor 116. In addition, the display 118 can provide a graphical interface for human-computer interaction for the user while displaying the ultrasound image, and one or more controlled objects are provided on the graphical interface, so that the user can input operation instructions by using the human-computer interaction device to control the controlled objects, thereby executing corresponding control operations. For example, an icon is displayed on the graphical interface, and the icon can be operated by the man-machine interaction device to execute a specific function, such as drawing a region-of-interest box on the ultrasonic image.

Optionally, the ultrasound imaging system 100 may further include a human-computer interaction device other than the display 118, which is connected to the processor 116, for example, the processor 116 may be connected to the human-computer interaction device through an external input/output port, which may be a wireless communication module, a wired communication module, or a combination thereof. The external input/output port may also be implemented based on USB, bus protocols such as CAN, and/or wired network protocols, etc.

The human-computer interaction device may include an input device for detecting input information of a user, for example, control instructions for the transmission/reception timing of the ultrasonic waves, operation input instructions for drawing points, lines, frames, or the like on the ultrasonic images, or other instruction types. The input device may include one or more of a keyboard, mouse, scroll wheel, trackball, mobile input device (e.g., mobile device with touch screen display, cell phone, etc.), multi-function knob, and the like. The human-computer interaction device may also include an output device such as a printer.

The ultrasound imaging system 100 may also include a memory 124 for storing instructions executed by the processor, storing received ultrasound echoes, storing ultrasound images, and so forth. The memory may be a flash memory card, solid state memory, hard disk, etc. Which may be volatile memory and/or non-volatile memory, removable memory and/or non-removable memory, etc.

It should be understood that the components included in the ultrasound imaging system 100 shown in fig. 1 are merely illustrative and that more or fewer components may be included. This is not a limitation of the present application.

The ultrasound-based blood flow measurement method proposed by the embodiment of the present application is described below with reference to fig. 2, and fig. 2 is a schematic flow chart of an ultrasound-based blood flow measurement method 200 according to the embodiment of the present application. The ultrasound-based blood flow measurement method 200 of an embodiment of the present application is used in an ultrasound imaging system including an ultrasound probe, a processor, and a display, which may be implemented as the ultrasound imaging system 100 described above. Specifically, the ultrasound-based blood flow measurement method 200 of the embodiment of the present application includes the following steps:

in step S210, controlling the ultrasound probe to emit a first ultrasound wave to a target region including a heart valve, and receiving an echo of the first ultrasound wave returned by the target region to obtain a first ultrasound echo signal;

in step S220, the processor performs signal processing on the first ultrasonic echo signal to obtain blood flow velocity information of the target region;

in step S230, the processor determines isovelocity information from the blood flow velocity information;

in step S240, the processor determines a constant velocity converging surface, the matching degree of which with a hemisphere or a semicircle meets a preset requirement, according to the constant velocity information;

in one embodiment, the processor fits the constant velocity information and determines a constant velocity convergence plane with a matching degree with a hemisphere or a semicircle meeting a preset requirement according to a result after fitting.

In one embodiment, the processor trains the constant velocity information through a deep learning network, and determines a constant velocity convergence plane with a matching degree with a hemisphere or a semicircle meeting a preset requirement according to an output result.

In step S250, the processor determines a first measurement parameter according to the isovelocity convergence surface, where the first measurement parameter includes an aliasing velocity obtained according to a blood flow velocity corresponding to the isovelocity convergence surface and a blood flow radius obtained according to a radius of the hemispherical or semicircular isovelocity convergence surface;

in step S260, the processor controls the display to display the first measurement parameter.

The ultrasound-based blood flow measurement method 200 of the embodiments of the present application can automatically implement abnormal blood flow quantification analysis based on the Proximal Isovelocity Surface Area (PISA) method. The PISA method is based on the principle of fluid proximal convergence and the principle of fluid continuity. The principle of proximal fluid convergence refers to the fact that when fluid passes through a narrow valve orifice (valve stenosis or regurgitation hole), blood flow converges to a concentric, high-speed, hemisphere-like, constant velocity converging surface, and the principle of fluid continuity refers to the fact that the flow passing through the constant velocity converging surface is equal to the flow passing through the narrow valve orifice. At present, in actual clinic, a doctor needs to manually adjust the speed range of color blood flow imaging, a hemispherical convergence surface is searched in a color blood flow image, and then manual measurement is carried out according to the convergence surface. The measuring process is largely adjusted manually, the subjectivity is strong, the operation process is complicated, and errors are easily caused for doctors with less experience. In contrast, the blood flow measuring method 200 based on ultrasound according to the embodiment of the present invention can automatically search for a constant velocity convergence plane, and thus, automatic measurement by the PISA method is achieved.

The embodiment of the invention is mainly used for quantitative analysis of heart valve regurgitation or valve stenosis. Among them, the regurgitation of the heart valve is mainly caused by the phenomenon that the structure or function of the heart valve cannot be normally closed due to some diseases or dysplasia, so that the blood in the heart flows reversely. Stenosis includes failure of the heart valve to open properly, resulting in an obstruction to blood flow.

Specifically, in step S210, the processor of the ultrasound imaging system controls the ultrasound probe to transmit a first ultrasonic wave to a target region including the heart valve and receive an echo of the first ultrasonic wave returned from the target region to obtain a first ultrasonic echo signal. The processor can control the ultrasonic imaging system to automatically enter a blood flow imaging mode when receiving a cardiac blood flow analysis instruction, and transmit and receive ultrasonic waves in the blood flow imaging mode. The beam synthesis module carries out corresponding processing such as focusing time delay, weighting and channel summation on the first ultrasonic echo signal, and then sends the first ultrasonic echo signal to the processor.

Then, in step S220, the processor performs signal processing on the first ultrasonic echo signal to obtain blood flow velocity information of the target region. Illustratively, the signals after beam synthesis are firstly subjected to quadrature demodulation, and strong tissue echo signals in the signals are filtered out through wall filtering processing, so that echo signals of blood cells are reserved; and then, the processor estimates parameters such as blood flow direction, speed and the like according to the filtered information to obtain blood flow speed information. For example, the processor may perform frame correlation, smoothing, etc. on the blood flow velocity information to improve the blood flow morphology, and allocate the primary colors according to the direction, velocity, etc. of the blood flow to obtain a color blood flow image. Generally, a color flow image is defined as a flow that is biased towards the ultrasound probe in red and a flow that is biased away from the ultrasound probe in blue. The color blood flow image may be a color blood flow image obtained by adjusting a speed range according to an aliasing rate, and the following may be specifically referred to.

In one embodiment, the processor first acquires a gray scale image of the cardiac tissue and determines the target region for color flow imaging from the gray scale image before controlling the ultrasound probe to emit the first ultrasound waves to the target region containing the heart valve. Specifically, the processor controls the ultrasonic probe to emit a third ultrasonic wave to the cardiac tissue and receives an echo of the third ultrasonic wave returned by the cardiac tissue to obtain a third ultrasonic echo signal; and the processor performs signal processing on the third ultrasonic echo signal to obtain a gray-scale image of the heart tissue.

Then, the processor determines a target area containing the heart valve according to the gray-scale image so as to automatically set a sampling frame of the blood flow imaging mode. Illustratively, the processor may employ machine learning methods to identify target regions in the grayscale image. Specifically, firstly, feature extraction is carried out on the gray-scale image, then the classifier is used for classifying the extracted features so as to determine the category of the image feature of each image block in the gray-scale image, and a target area is divided in the gray-scale image according to the category of the image block. Or, based on an end-to-end deep learning neural network of deep learning, learning features of a pre-constructed database is performed by stacking convolutional layers and fully-connected layers, and an up-sampling layer or an anti-convolutional layer is added to enable the input size and the output size to be the same, so that a target region and a corresponding category of an input image are directly obtained. Alternatively, the processor may also determine the target region in the grayscale image using conventional image segmentation algorithms.

After the target region is identified, in step S230, the processor may control to automatically switch from the grayscale imaging mode to the blood flow imaging mode (i.e., C mode), and acquire the blood flow velocity information in the blood flow imaging mode, so as to perform quantitative analysis on abnormal blood flow based on the blood flow velocity information. Optionally, the processor may also switch from the grayscale imaging mode to the flow imaging mode according to the received mode switching instruction.

Specifically, in the quantitative analysis process, the processor first executes step S230 and step S240 to automatically acquire the constant velocity convergence surface according to the blood flow velocity information. Wherein:

in step S230, the processor determines isovelocity information from the blood flow velocity information. The constant velocity information includes a constant velocity line or a constant velocity plane. The isovelocity line is a continuous straight line or curve, and the blood flow velocity values of any two points on the same isovelocity line are basically equal. When the blood flow velocity information is two-dimensional blood flow velocity information, the isovelocity information includes an isovelocity line. When the blood flow velocity information is three-dimensional blood flow velocity information, the isovelocity information mainly includes an isovelocity plane, but may alternatively include an isovelocity line. The isovelocity surface is a continuous plane or curved surface, and the blood flow velocity values of any two points on the same isovelocity surface are basically equal.

Taking the isovelocity line as an example, isovelocity information can be determined from the blood flow velocity information by using any contour drawing method. For example, the blood flow velocity information is first subjected to isoline meshing, the minimum value and the maximum value of the spatial coordinates of the blood flow velocity information are taken as boundaries, the blood flow velocity information is divided into rectangular meshes, and the blood flow velocity value of each mesh point is obtained by an interpolation algorithm; then, constant velocity line tracking is carried out, equivalent points are searched around each grid point, and the equivalent points in the blood flow velocity information are connected; and finally, smoothing and filling the connected equivalence points to obtain a continuous contour line.

Next, in step S240, in an embodiment, the processor fits the constant velocity information, and determines a constant velocity converging surface having a matching degree with the hemisphere or the semicircle meeting a preset requirement according to a result of the fitting. When the blood flow velocity information is two-dimensional blood flow velocity information, the processor adopts a preset algorithm to perform semi-circle fitting on the constant velocity line so as to determine the constant velocity convergence surface with the highest matching degree with the semi-circle, namely, the processor performs fitting on the constant velocity line so as to find the constant velocity convergence surface (the surface is approximate to the semi-circle) which is closest to the semi-circle (namely, the fitting error is minimum). When the blood flow velocity information is three-dimensional blood flow velocity information, the processor performs hemispherical fitting on the constant velocity surface to determine a constant velocity convergence surface with the highest matching degree with the hemisphere, namely, the processor performs fitting on the constant velocity surface to find the constant velocity convergence surface (which is approximate to a spherical surface) closest to the hemisphere (i.e., with the smallest fitting error). Therefore, the user does not need to manually adjust the speed range of color blood flow imaging, the processor of the ultrasonic imaging system automatically realizes the detection of the constant-speed convergence surface, the step of manually adjusting the speed range by the user is omitted, and errors caused by the subjectivity of operators can be avoided. Illustratively, the fitting process may be implemented by a least square method, a hough transform, or RANSAC. Similarly, the isokinetic information may also be processed correspondingly by using a deep learning network or other methods to find the isokinetic convergence plane closest to the semicircle or the hemisphere (i.e., with the smallest matching error), which will not be described in detail herein.

Based on the above steps S230 and S240, the processor automatically searches for a constant velocity converging surface from the blood flow velocity information. On the basis of the isovelocity convergence surface, the processor determines a first measurement parameter according to the isovelocity convergence surface and controls the display to display the first measurement parameter at step S250. The first measurement parameter comprises an aliasing velocity Va and a blood flow radius r, wherein the aliasing velocity Va is obtained according to the blood flow velocity corresponding to the constant-velocity convergence surface, and the blood flow radius r is obtained according to the radius of the hemispherical or semicircular constant-velocity convergence surface. The surface area of the hemispherical or semicircular isokinetic convergence surface can be obtained according to the blood flow radius r, and the blood flow rate RegFlow, i.e. the instantaneous flow rate through the isokinetic convergence surface, can be obtained by multiplying the surface area by the aliasing velocity Va. The processor may also control the display to display the blood flow rate.

Further, in order to realize complete evaluation of the PISA method, after the aliasing velocity Va and the blood flow radius r are obtained, the doppler spectrum of the position where the abnormal blood flow is located can be acquired, and other measurement parameters for performing quantitative evaluation on the abnormal blood flow are obtained according to the doppler spectrum.

The Doppler frequency spectrum can be a continuous Doppler frequency spectrum, the sampling position of the continuous Doppler frequency spectrum is a sampling line of the continuous Doppler frequency spectrum, and the sampling line can pass through the spherical center of the hemispherical constant-speed converging surface or the circle center of the semicircular constant-speed converging surface. When acquiring the continuous Doppler frequency spectrum, one group of transducer elements continuously transmits second ultrasonic waves, and the other group of transducer elements continuously receives second ultrasonic echo signals. The continuous Doppler frequency spectrum has high speed resolution capability, can detect high-speed blood flow, and is more suitable for the characterization of high-speed abnormal blood flow.

Wherein the sampling location of the doppler spectrum can be automatically determined by the processor based on the isovelocity convergence plane. Referring to fig. 4A, the processor first determines the abnormal blood flow position (i.e., the position of the regurgitant orifice or the position of the valve stenosis) according to the isovelocity convergence plane, and sets the sampling position of the doppler spectrum according to the abnormal blood flow position. Then, referring to fig. 4B, the processor controls the ultrasonic probe to emit a second ultrasonic wave to the target region based on the sampling position and receives an echo of the second ultrasonic wave returned by the target region to obtain a second ultrasonic echo signal; the processor performs signal processing on the second ultrasonic echo signal to obtain a Doppler spectrum at the sampling position, and controls the display to display the Doppler spectrum.

Illustratively, after setting the sampling position, the processor can control to automatically enter a Doppler spectrum imaging mode to obtain a Doppler spectrum. Alternatively, the processor may control the display to mark the sampling position on the color blood flow image, and enter a doppler spectrum imaging mode after receiving a confirmation instruction of the sampling position to obtain the doppler spectrum. If the user thinks that the sampling position has deviation, the mark of the sampling position can be adjusted, and the processor generates the Doppler frequency spectrum according to the sampling position adjusted by the user.

After the Doppler frequency spectrum is obtained, the processor performs frequency spectrum analysis on the Doppler frequency spectrum to obtain a second measurement parameter of abnormal blood flow. For example, the processor may automatically analyze the doppler spectrum based on a spectrum analysis method such as the tsujin threshold method, first perform threshold segmentation on the doppler spectrum to obtain a spectrum envelope, and obtain a second measurement parameter according to the segmented spectrum envelope. And then, the processor obtains an accurate abnormal blood flow quantification parameter according to the first measurement parameter and the second measurement parameter, and controls the display to display the abnormal blood flow quantification parameter.

In one embodiment, the second measured parameter comprises a maximum abnormal blood flow velocity PKreg, which is derived from a peak of the doppler spectrum. The processor may perform peak identification on the spectral envelope of the doppler spectrum to obtain the maximum abnormal blood flow velocity PKreg.

According to the current abnormal blood flow evaluation guideline, the abnormal blood flow quantification parameter comprises an effective abnormal structure area, specifically an effective regurgitation hole area or a valve stenosis area. According to the principle of continuity of fluid flow, in a closed system, the instantaneous flow rate of fluid flowing through one interface is equal to the flow rate flowing through another section at the same time, i.e. the flow rate of blood flowing through the isovelocity convergence plane is equal to the flow rate flowing through an abnormal blood flow structure. Thus, the effective abnormal structural area EROA is obtained based on the ratio of the reflux flow rate to the maximum abnormal blood flow velocity PKreg.

Specifically, the calculation process of the effective abnormal structure area EROA includes the following steps:

firstly, the surface area of the constant-speed converging surface is obtained according to the blood flow radius r: a =2 π r ² ；

Then, the aliasing velocity Va and the surface area 2 π r of the isovelocity converging surface are determined ² Obtaining the blood flow rate through the isokinetic convergence plane: regFlow =2 pi r2 Va;

then, the effective abnormal structural area EROA is obtained according to the ratio of the blood flow rate RegFlow to the maximum abnormal blood flow velocity PKreg: EROA = RegFlow/PKVreg.

Further, the abnormal blood flow quantification parameter further includes an abnormal blood flow RVol, i.e., a blood flow through an effective abnormal structure. To obtain abnormal blood flow, the second measurement parameter further comprises an abnormal blood flow velocity time integral VTIreg. The processor performs spectrum analysis on the Doppler spectrum to obtain an abnormal blood flow velocity time integral VTIreg, and then obtains an abnormal blood flow volume RVol according to the product of the effective abnormal structure area EROA and the abnormal blood flow velocity time integral VTIreg, namely RVol = EROA VTIreg.

In one embodiment, after obtaining the abnormal blood flow quantification parameters such as the effective abnormal structural area EROA and the abnormal blood flow volume RVol, the processor may further obtain an abnormal blood flow degree grade according to the abnormal blood flow quantification parameters, and control the display to display the abnormal blood flow degree grade. Taking reflux as an example, the processor can also measure the width VCW of the narrowest part of the reflux stream according to the color blood flow image; measuring a regurgitation area in the color blood flow image, measuring a left atrium area in the gray-scale image, and obtaining a regurgitation fraction RF according to a ratio of the regurgitation area to the left atrium area; and combining abnormal blood flow quantification parameters such as effective abnormal structure area EROA, abnormal blood flow RVol, width VCW of the narrowest part of the regurgitation beam, regurgitation fraction RF and the like to obtain abnormal blood flow degree grading.

The processor performs quantitative analysis on abnormal blood flow on one hand, and can perform ultrasonic imaging on an abnormal blood flow region according to the result of the quantitative analysis on the other hand. Specifically, the processor adjusts a velocity range of color flow imaging according to the aliasing velocity Va, generates a color flow image based on the blood flow velocity information according to the adjusted velocity range, and controls the display to display the color flow image so as to display the isovelocity convergence plane by the color flow image. In the conventional PISA method measurement scheme, a doctor needs to manually adjust the speed range of color blood flow imaging, and a hemispherical convergence surface is searched in a color blood flow image for measurement; according to the embodiment of the invention, the aliasing speed Va is automatically acquired firstly, the speed range of the color blood flow imaging is adjusted according to Va, the manual adjustment process of a doctor is omitted, the visual constant-speed convergence surface can be directly presented to a user, and the adjustment result is more accurate.

Illustratively, adjusting the velocity range for color flow imaging based on the aliasing velocity Va includes: the aliasing velocity Va is set as one of the boundary values of the velocity range. Specifically, if the speed range before adjustment is [ V1, V2], the speed range after adjustment is [ V1, va ] or [ Va, V2]. Setting the aliasing velocity Va to the maximum or minimum of the boundary values depends on the valve type, and setting the velocity range to [ Va, V2] better highlights the isovelocity convergence plane for mitral regurgitation. Wherein, V1, V2 can be the preset value that sets up according to the physical range, also can be for the doctor adjust the range that obtains according to self experience.

Since the ultrasound-based blood flow measurement method 200 of the embodiment of the present invention involves switching of a plurality of ultrasound imaging modes, such as switching from a grayscale imaging mode to a color flow imaging mode and switching from a color flow imaging mode to a doppler spectrum imaging mode, in order to operate the ultrasound probe, in the above measurement process, the processor may further control the display to display a scanning guide, which includes the name of a slice to be scanned and the corresponding ultrasound imaging mode. All the ultrasonic imaging modes (namely a gray scale imaging mode, a color flow imaging mode and a Doppler spectrum imaging mode) can be displayed at one time, and the next ultrasonic imaging mode to be entered can be displayed after the measurement in one ultrasonic imaging mode is completed.

The processor may further control the display to display an evaluation guide including each of the first measurement parameter and the second measurement parameter. The measurement parameters that have been measured and have not started to be measured can be displayed in a first display mode, and the measurement parameters currently being measured can be displayed in a second display mode, so that a user can know the measurement progress and confirm the measurement parameters. For example, before the measurement starts, the processor may control the display to display names of aliasing velocity, blood flow radius, maximum abnormal blood flow velocity and abnormal blood flow velocity time integral, and display the corresponding measurement value after the names of aliasing velocity and blood flow radius are obtained by the measurement.

In summary, the blood flow measurement method 200 based on ultrasound according to the embodiment of the present application can automatically implement blood flow quantification analysis based on the proximal isovelocity surface area method.

The embodiment of the present application further provides an ultrasound imaging system, which is used for implementing the blood flow measurement method 200 based on ultrasound. The ultrasound imaging system includes an ultrasound probe, a transmit circuit, a receive circuit, a processor, and a display. Referring back to fig. 1, the ultrasound imaging system may be implemented as the ultrasound imaging system 100 shown in fig. 1, the ultrasound imaging system 100 may include an ultrasound probe 110, a transmitting circuit 112, a receiving circuit 114, a processor 116, and a display 118, optionally, the ultrasound imaging system 100 may further include a transmitting/receiving selection switch 120 and a beam forming module 122, the transmitting circuit 112 and the receiving circuit 114 may be connected to the ultrasound probe 110 through the transmitting/receiving selection switch 120, and the description of each component may refer to the above description, which is not repeated herein.

Wherein, the transmitting circuit 112 is used for controlling the ultrasonic probe 110 to transmit ultrasonic waves to a target area containing a heart valve; the receiving circuit 114 is used for controlling the ultrasonic probe 110 to receive the echo of the ultrasonic wave returned by the target region so as to obtain an ultrasonic echo signal; the processor 116 is configured to perform ultrasound imaging based on the ultrasound echo signals; the processor 116 is further configured to perform the ultrasound-based blood flow measurement method 200 described above, including: controlling the ultrasonic probe 110 to emit a first ultrasonic wave to a target area containing a heart valve and receive an echo of the first ultrasonic wave returned by the target area to obtain a first ultrasonic echo signal; performing signal processing on the first ultrasonic echo signal to obtain blood flow velocity information of a target area; determining constant velocity information according to the blood flow velocity information; fitting the constant speed information, and determining a constant speed convergence surface of which the matching degree with the hemisphere or the semicircle meets the preset requirement according to the fitting result; determining a first measurement parameter according to the isokinetic convergence surface, wherein the first measurement parameter comprises aliasing velocity and blood flow radius, the aliasing velocity is obtained according to the blood flow velocity corresponding to the isokinetic convergence surface, and the blood flow radius is obtained according to the radius of a hemispherical or semicircular isokinetic convergence surface; the display 118 is controlled to display the first measured parameter. The display 118 is used to display data output by the processor, including but not limited to the first measured parameter.

In one embodiment, the isovelocity information includes an isovelocity line or an isovelocity surface; fitting the constant speed information, and determining a constant speed convergence surface meeting preset requirements with a hemispherical or semicircular matching degree according to the result after fitting, wherein the constant speed convergence surface comprises the following components: and performing semi-circle fitting on the constant speed line by adopting a preset algorithm to determine a constant speed convergence surface with the highest matching degree with the semi-circle, or performing semi-sphere fitting on the constant speed surface by adopting the preset algorithm to determine the constant speed convergence surface with the highest matching degree with the semi-sphere.

In one embodiment, the processor 116 is further configured to: determining the position of abnormal blood flow according to the constant-speed convergence surface; setting a sampling position of a Doppler frequency spectrum according to the abnormal blood flow position; controlling the ultrasonic probe 110 to emit a second ultrasonic wave to the target region based on the sampling position and receive an echo of the second ultrasonic wave returned from the target region to obtain a second ultrasonic echo signal; performing signal processing on the second ultrasonic echo signal to obtain a Doppler frequency spectrum at the sampling position; performing spectrum analysis on the Doppler spectrum to obtain a second measurement parameter of abnormal blood flow; and obtaining abnormal blood flow quantification parameters according to the first measurement parameters and the second measurement parameters, and controlling a display to display the abnormal blood flow quantification parameters.

In one embodiment, the second measurement parameter includes a maximum abnormal blood flow velocity, the maximum abnormal blood flow velocity is obtained according to a peak value of the doppler spectrum, the abnormal blood flow quantification parameter includes an effective abnormal structural area, and the abnormal blood flow quantification parameter is obtained according to the first measurement parameter and the second measurement parameter, and includes: obtaining the surface area of the constant-speed convergence surface according to the radius of the blood flow; obtaining the blood flow rate through the isovelocity convergence plane according to the aliasing velocity and the surface area; and obtaining the effective abnormal structure area according to the ratio of the blood flow rate to the maximum abnormal blood flow velocity.

In one embodiment, the second measurement parameter further includes an abnormal blood flow velocity time integral, the abnormal blood flow quantification parameter further includes an abnormal blood flow, and the abnormal blood flow quantification parameter is obtained according to the first measurement parameter and the second measurement parameter, and further includes: and obtaining the abnormal blood flow according to the product of the effective abnormal structural area and the time integral of the abnormal blood flow velocity.

In one embodiment, the processor 116 is further configured to: and obtaining abnormal blood flow degree grading according to the abnormal blood flow quantification parameter, and controlling the display 118 to display the abnormal blood flow degree grading.

In one embodiment, the processor 116 is further configured to: adjusting the speed range of the color blood flow imaging according to the aliasing speed; generating a color blood flow image based on the blood flow velocity information according to the adjusted velocity range; and controlling the display to display the color blood flow image so as to display the constant-speed convergence surface through the color blood flow image.

In one embodiment, adjusting a velocity range of color flow imaging based on aliasing velocity comprises: the aliasing velocity is set to one of the boundary values of the velocity range.

In one embodiment, the processor 116 is further configured to: after the sampling position is set, a Doppler spectrum imaging mode is automatically entered to obtain a Doppler spectrum, or after a confirmation instruction of the sampling position is received, the Doppler spectrum imaging mode is entered to obtain the Doppler spectrum.

In one embodiment, before controlling the ultrasound probe 110 to emit the first ultrasound waves to the target region including the heart valve, the processor 116 is further configured to: controlling the ultrasonic probe 110 to emit a third ultrasonic wave to the cardiac tissue and receive an echo of the third ultrasonic wave returned by the cardiac tissue to obtain a third ultrasonic echo signal; processing the third ultrasonic echo signal to obtain a gray scale image of the heart tissue; a target region containing a heart valve is determined from the grayscale image.

In one embodiment, the processor 116 is further configured to: the control display 118 displays a scan guide that includes the name of the slice to be scanned and the corresponding ultrasound imaging mode.

In one embodiment, the processor 116 is further configured to: the control display 118 displays an evaluation guide including each of the first measurement parameter and the second measurement parameter, in which the measurement parameters that have been completed and have not started to be measured are displayed in a first display manner, and the measurement parameter that is currently being measured is displayed in a second display manner.

In one embodiment, the abnormal blood flow location comprises a regurgitant orifice location or a valve stenosis.

Only the main functions of the components of the ultrasound imaging system are described above, and for more details, reference is made to the related description of the ultrasound-based blood flow measurement method 200, which is not described herein again.

The ultrasonic imaging system of the embodiment of the application can automatically realize abnormal blood flow analysis by adopting a near-end constant-velocity surface area method.

Although the example embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the above-described example embodiments are merely illustrative and are not intended to limit the scope of the present application thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present application. All such changes and modifications are intended to be included within the scope of the present application as claimed in the appended claims.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the technical solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described device embodiments are merely illustrative, and for example, the division of the units is only one type of logical functional division, and other divisions may be realized in practice, for example, multiple units or components may be combined or integrated into another device, or some features may be omitted, or not executed.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the application may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Similarly, it should be appreciated that in the description of exemplary embodiments of the present application, various features of the present application are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the application and aiding in the understanding of one or more of the various inventive aspects. However, the method of this application should not be construed to reflect the intent: this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this application.

It will be understood by those skilled in the art that all of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where such features are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

Moreover, those of skill in the art will understand that although some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

Various component embodiments of the present application may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art will appreciate that a microprocessor or Digital Signal Processor (DSP) may be used in practice to implement some or all of the functionality of some of the modules according to embodiments of the present application. The present application may also be embodied as apparatus programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present application may be stored on a computer readable medium or may be in the form of one or more signals. Such a signal may be downloaded from an internet website, or provided on a carrier signal, or provided in any other form.

It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The application may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.

The above description is only for the specific embodiments of the present application or the description thereof, and the protection scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope disclosed in the present application, and shall be covered by the protection scope of the present application. The protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An ultrasound-based blood flow measurement method for an ultrasound imaging system comprising an ultrasound probe, a processor and a display, the method comprising:

controlling the ultrasonic probe to emit first ultrasonic waves to a target area containing a heart valve and receive echoes of the first ultrasonic waves returned by the target area to obtain a first ultrasonic echo signal;

the processor performs signal processing on the first ultrasonic echo signal to obtain blood flow velocity information of the target area;

the processor determines isovelocity information according to the blood flow velocity information;

the processor fits the constant speed information and determines a constant speed convergence surface of which the matching degree with the hemisphere or the semicircle meets the preset requirement according to the fitting result;

the processor determines a first measurement parameter according to the isokinetic convergence surface, wherein the first measurement parameter comprises an aliasing velocity and a blood flow radius, the aliasing velocity is obtained according to the blood flow velocity corresponding to the isokinetic convergence surface, and the blood flow radius is obtained according to the radius of the hemispherical or semicircular isokinetic convergence surface;

the processor controls the display to display the first measurement parameter.

2. An ultrasound-based blood flow measurement method for an ultrasound imaging system comprising an ultrasound probe, a processor and a display, the method comprising:

the processor determines isokinetic information according to the blood flow velocity information;

the processor determines a constant-speed convergence surface which meets the preset requirement in the matching degree with the hemisphere or the semicircle according to the constant-speed information;

the processor determines a first measurement parameter according to the isokinetic convergence surface, wherein the first measurement parameter comprises an aliasing velocity and a blood flow radius, the aliasing velocity is obtained according to a blood flow velocity corresponding to the isokinetic convergence surface, and the blood flow radius is obtained according to the radius of the hemispherical or semicircular isokinetic convergence surface;

the processor controls the display to display the first measurement parameter.

3. The method of claim 1, wherein the isovelocity information comprises an isovelocity line or an isovelocity surface; the constant velocity information is fitted, and a constant velocity convergence surface which meets preset requirements with the matching degree of a hemisphere or a semicircle is determined according to the fitting result, and the method comprises the following steps:

and performing semi-circle fitting on the constant speed line by adopting a preset algorithm to determine a constant speed convergence surface with the highest matching degree with a semi-circle, or performing semi-sphere fitting on the constant speed surface by adopting the preset algorithm to determine the constant speed convergence surface with the highest matching degree with the semi-circle.

4. The method of claim 1 or 2, further comprising:

the processor determines the position of abnormal blood flow according to the constant-speed convergence surface;

the processor sets a sampling position of a Doppler frequency spectrum according to the abnormal blood flow position;

the processor controls the ultrasonic probe to emit a second ultrasonic wave to the target area based on the sampling position and receives an echo of the second ultrasonic wave returned by the target area to obtain a second ultrasonic echo signal;

the processor performs signal processing on the second ultrasonic echo signal to obtain a Doppler frequency spectrum at the sampling position;

the processor performs spectrum analysis on the Doppler spectrum to obtain a second measurement parameter of abnormal blood flow;

and the processor obtains an abnormal blood flow quantification parameter according to the first measurement parameter and the second measurement parameter, and controls the display to display the abnormal blood flow quantification parameter.

5. The method of claim 4, wherein the second measurement parameter comprises a maximum abnormal blood flow velocity, the maximum abnormal blood flow velocity being derived from a peak of the Doppler spectrum, the abnormal blood flow quantification parameter comprising an effective abnormal structural area,

the obtaining of the abnormal blood flow quantification parameter according to the first measurement parameter and the second measurement parameter includes:

obtaining the surface area of the constant-speed converging surface according to the blood flow radius;

obtaining a blood flow rate through the isovelocity collection surface from the aliasing velocity and the surface area;

and obtaining the effective abnormal structure area according to the ratio of the blood flow rate to the maximum abnormal blood flow velocity.

6. The method of claim 5, wherein the second measured parameter further comprises an abnormal blood flow velocity time integral, wherein the abnormal blood flow quantification parameter further comprises an abnormal blood flow, wherein obtaining the abnormal blood flow quantification parameter from the first measured parameter and the second measured parameter further comprises:

and obtaining the abnormal blood flow according to the product of the effective abnormal structure area and the time integral of the abnormal blood flow velocity.

7. The method of claim 4, further comprising:

and the processor obtains abnormal blood flow degree grading according to the abnormal blood flow quantification parameters and controls the display to display the abnormal blood flow degree grading.

8. The method of claim 1 or 2, further comprising:

the processor adjusts the speed range of color blood flow imaging according to the aliasing speed;

generating a color blood flow image based on the blood flow velocity information according to the adjusted velocity range;

controlling the display to display the color blood flow image so as to display the constant velocity convergence surface through the color blood flow image.

9. The method of claim 8, wherein said adjusting a velocity range of color flow imaging based on the aliasing velocity comprises:

setting the aliasing velocity to one of the boundary values of the velocity range.

10. The method of claim 4, further comprising:

after the sampling position is set, automatically entering a Doppler spectrum imaging mode to obtain the Doppler spectrum, or entering the Doppler spectrum imaging mode after receiving a confirmation instruction of the sampling position to obtain the Doppler spectrum.

11. The method of claim 1 or 2, wherein prior to controlling the ultrasound probe to emit the first ultrasound waves to the target region containing the heart valve, the method further comprises:

controlling the ultrasonic probe to emit a third ultrasonic wave to the heart tissue and receive an echo of the third ultrasonic wave returned by the heart tissue to obtain a third ultrasonic echo signal;

the processor performs signal processing on the third ultrasonic echo signal to obtain a gray scale image of the cardiac tissue;

the processor determines the target region containing a heart valve from the grayscale image.

12. The method of claim 1 or 2, further comprising:

the processor controls the display to display a scanning guide, and the scanning guide comprises the name of a section to be scanned and a corresponding ultrasonic imaging mode.

13. The method of claim 4, further comprising:

the processor controls the display to display an evaluation guide including each of the first and second measurement parameters, wherein the measurement parameters that have been completed and have not started to be measured are displayed in a first display manner, and the measurement parameters that are currently being measured are displayed in a second display manner.

14. The method of claim 4, wherein the abnormal blood flow location comprises a regurgitant orifice location or a valve stenosis.

15. An ultrasound imaging system, comprising an ultrasound probe, transmit circuitry, receive circuitry, a processor, and a display, wherein:

the transmitting circuit is used for controlling the ultrasonic probe to transmit ultrasonic waves to a target area containing a heart valve;

the receiving circuit is used for controlling the ultrasonic probe to receive the echo of the ultrasonic wave returned by the target area so as to obtain an ultrasonic echo signal;

the processor is used for carrying out ultrasonic imaging based on the ultrasonic echo signal;

the processor is further configured to perform the ultrasound-based blood flow measurement method of any one of claims 1-14;

the display is used for displaying the data output by the processor.