Method and device for improving strain displacement accuracy of medical color ultrasound equipment

Abstract

The application provides a method and device for improving strain displacement precision of a medical color ultrasound equipment, wherein the method comprises the following steps: S11, front-end cross-transmitting and receiving multi-angle ultrasonic wave carrier signals to obtain baseband original echo signals in a user interested area; S12, sparsely sampling the baseband original echo signals before and after deformation along each angle scanning line direction; S13, obtaining original baseband echo signals in the same direction before and after deformation according to time intervals before and after deformation; S14, point-by-point Doppler velocity estimation is performed on multi-frame sparsely sampled baseband signals in the same angle and different time along the scanning line and time direction; S15, calculating accurate displacement frames according to the displacement sequence frames in each angle; and S16, obtaining displacement sequence frames in each angle according to the Doppler velocities in each angle. The application uses a cross multi-angle scanning mode to calculate tissue velocity and displacement by using the Doppler principle, and improves the precision of tissue displacement on the basis of minimizing data amount.

Description

Technical Field

[0001] This invention relates to the field of medical color Doppler ultrasound technology, and in particular to a method and apparatus for improving the strain displacement accuracy of medical color Doppler ultrasound equipment. Background Technology

[0002] Currently, in medical color Doppler ultrasound systems, ultrasound elastography utilizes sound waves to detect the stiffness properties of tissues. In existing technology, an ultrasound probe is placed on the human body surface. The heart's beat causes tissue movement and deformation. When tissue is compressed, a strain is generated along the longitudinal compression direction of the probe. If the elastic modulus distribution within the tissue is uneven, the strain distribution will also differ. Areas with a high elastic modulus will have smaller strain and less deformation, meaning less tissue movement; conversely, areas with a low elastic modulus will have larger strain and greater deformation, resulting in more tissue movement. The ultrasound probe continuously receives signals from the deforming tissue. After processing by the ultrasound host, these signals are generated as continuous frames. By processing these frames, the displacement distribution of the tissue at different times is obtained. This displacement is then mapped to stiffness, visually representing the distribution of the elastic modulus and thus describing the physiological and pathological state of the tissue. The method of generating a hardness map by inducing tissue deformation through cardiac pulsation is called quasi-static elastography. This imaging method is affected by the human heart's pulsation, which causes tissue deformation to have arbitrary directions, resulting in inaccurate final hardness measurements. Correspondingly, the imaging algorithms generally only consider calculating tissue hardness information along the longitudinal direction of the probe. However, actual tissue deformation will produce displacement information in the lateral, longitudinal, or other directions. Therefore, we need a more accurate elastography strain imaging method.

[0003] This patent aims to propose an easy-to-implement, real-time, and high-precision strain force imaging method that can be conveniently and quickly deployed in medical color Doppler ultrasound equipment systems. Summary of the Invention

[0004] One objective of this invention is to provide a method for improving the strain displacement accuracy of medical color Doppler ultrasound equipment, which can meet the imaging needs of various probes such as linear array, convex array, and phased array. This patent employs a cross-multi-angle scanning method and uses the Doppler principle to calculate tissue velocity and displacement, improving the accuracy of tissue displacement while minimizing data volume, and facilitating rapid transmission to the backend for processing and display.

[0005] This invention provides a method for improving the strain displacement accuracy of a medical color Doppler ultrasound device, comprising:

[0006] S11. The front end cross-transmits and receives multi-angle ultrasonic carrier signals to obtain the baseband raw echo signal within the user's region of interest; the baseband raw echo signal includes: baseband raw signal frames before and after tissue deformation.

[0007] S12. Sparsely sample the baseband original echo signal before and after deformation along the scanning line direction at each angle.

[0008] S13. Obtain the original baseband echo signals in the same direction before and after deformation based on the time interval before and after deformation.

[0009] S14. Perform point-by-point Doppler velocity estimation on the multi-frame sparsely sampled baseband signals at different times and angles along the scan line and time direction.

[0010] S15. Calculate the precise displacement frame based on the displacement sequence frames of each angle;

[0011] S16. Calculate the displacement sequence frames of each angle based on the Doppler velocity at each angle.

[0012] Preferably, the front end cross-transmits and receives multi-angle ultrasonic carrier signals. The cross-transmit and receive method can act on the entire region of interest at once or on the region of interest multiple times. The required transmission and reception angles include positive or negative angles within zero angle.

[0013] Preferably, the baseband raw echo signals acquired by the user within the region of interest have equal and adjustable time intervals between adjacent frames, and similarly, the time intervals between each receiving line are also equal.

[0014] Preferably, both the baseband original signal frames before and after deformation contain multiple baseband original signal frames with positive or negative angles within zero angle.

[0015] Preferably, sparse sampling involves resampling the original baseband signal frame based on the width, depth, and height of the region of interest.

[0016] Preferably, Doppler velocity is first calculated for frame data at the same angle in the time direction. The Doppler velocity calculation method can be autocorrelation, cross-correlation, or other velocity calculation formulas. Then, the Doppler velocity in the depth direction is calculated point by point or jump point along the receiving line direction to obtain a velocity signal frame.

[0017] Preferably, velocity frames at different angles form a velocity frame sequence, and a displacement frame sequence is calculated from the velocity frame sequence and the inter-frame time interval. In the displacement frame sequence, the zero-angle displacement frame is used as the reference frame, and each positive or negative angle displacement frame is a dynamic frame. The reference frame is calibrated using each dynamic frame to obtain an accurate displacement frame.

[0018] This invention provides a device for improving the strain displacement accuracy of a medical color Doppler ultrasound device, comprising:

[0019] The original adjacent baseband signal frame acquisition module S21 is used to acquire the original baseband echo signal within the user's region of interest by front-end cross-transmission and reception of multi-angle ultrasonic carrier signals; the original baseband echo signal includes: the original baseband signal frames before and after tissue deformation.

[0020] The region of interest resampling module S22 is used to sparsely sample the original baseband echo signals before and after deformation along the scanning line direction at each angle, and obtain the original baseband echo signals in the same direction before and after deformation according to the time interval before and after deformation.

[0021] The same-angle velocity frame calculation module S23 is used to perform point-by-point Doppler velocity estimation of multiple frames of sparsely sampled baseband signals at different times with the same angle along the scan line and time direction.

[0022] The same angle displacement frame calculation module S24 is used to calculate the accurate displacement frame based on the displacement sequence frames of each angle.

[0023] The precise displacement acquisition module S25 is used to calculate and obtain displacement sequence frames at each angle based on the Doppler velocity at each angle.

[0024] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0027] Figure 1 This is a flowchart illustrating a method for improving strain displacement accuracy in a medical color Doppler ultrasound device according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of a device for improving strain displacement accuracy in a medical color Doppler ultrasound device according to an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of a front-end scanning frame sequence in one embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of a scan line sequence in one embodiment of the present invention;

[0031] Figure 5This is a schematic diagram of in-box resampling in one embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of displacement change in one embodiment of the present invention;

[0033] Figure 7 This is a schematic diagram of precise displacement synthesis calculation in one embodiment of the present invention. Detailed Implementation

[0034] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0035] First, let's explain the relevant terms:

[0036] Beamforming: Combining multiple ultrasonic signals into a single signal is called beamforming.

[0037] Delay parameter: When multiple ultrasonic waves arrive at the target point, they arrive in a certain order. The time difference between these arrival times is the delay parameter.

[0038] Dynamic reception: In medical color ultrasound equipment, the direction of ultrasound transmission is artificially defined as the axis. A segment of ultrasound is collected along the axis at short intervals. This reception method is called dynamic reception.

[0039] Focusing: When multiple ultrasonic signals arrive at a certain depth along the axis at the same time, it is called focusing.

[0040] Beam: The ultrasonic signal after beamforming is called a beam, which can also be called a beamline or a line, etc.

[0041] RF data: The final data after beamforming;

[0042] Strain force: When tissue is compressed, different types of tissue deform differently. Strain force is used to measure tissue stiffness.

[0043] This invention provides a method for improving the strain displacement accuracy of medical color Doppler ultrasound equipment, such as... Figure 1 As shown, it includes:

[0044] S11. The front end cross-transmits and receives multi-angle ultrasonic carrier signals to obtain the baseband raw echo signal within the user's region of interest; the baseband raw echo signal includes: baseband raw signal frames before and after tissue deformation.

[0045] S12. Sparsely sample the baseband original echo signal before and after deformation along the scanning line direction at each angle.

[0046] S13. Obtain the original baseband echo signals in the same direction before and after deformation based on the time interval before and after deformation.

[0047] S14. Perform point-by-point Doppler velocity estimation on the multi-frame sparsely sampled baseband signals at different times and angles along the scan line and time direction.

[0048] S15. Calculate the precise displacement frame based on the displacement sequence frames of each angle;

[0049] S16. Calculate the displacement sequence frames of each angle based on the Doppler velocity at each angle.

[0050] The front end cross-transmits and receives multi-angle ultrasonic carrier signals. Its cross-transmit and receive mode can act on the entire region of interest at once or on the region of interest multiple times. The required transmission and reception angles include positive or negative angles within zero angle.

[0051] The baseband raw echo signal acquired by the user within the region of interest has equal and adjustable time intervals between adjacent frames, and similarly, the time intervals between each receiving line are also equal.

[0052] Both the baseband raw signal frames before and after deformation contain multiple baseband raw signal frames with positive or negative angles within zero angle.

[0053] Sparse sampling is the resampling of the original baseband signal frame based on the width, depth, and height of the region of interest.

[0054] First, Doppler velocity is calculated for frame data at the same angle in the time direction. The Doppler velocity calculation method can be autocorrelation, cross-correlation, or other velocity calculation formulas. Then, the Doppler velocity in the depth direction is calculated point by point or jump point along the receiving line direction to obtain a velocity signal frame.

[0055] Velocity frames at different angles form a velocity frame sequence. The displacement frame sequence is calculated from the velocity frame sequence and the inter-frame time interval. In the displacement frame sequence, the zero-angle displacement frame is used as the reference frame, and each positive or negative angle displacement frame is a dynamic frame. The reference frame is calibrated using each dynamic frame to obtain an accurate displacement frame.

[0056] The working principle and beneficial effects of the above technical solution are as follows:

[0057] like Figure 1 As shown, the S11 front end cross-transmits and receives multi-angle ultrasonic carrier signals to acquire the baseband raw echo signal within the user's region of interest;

[0058] A feasible method for cross-transmitting and receiving multi-angle ultrasonic carriers, such as Figure 4As shown, the crossover mode can transmit and receive between frames. S41, S42, and S43 are negative angle, zero angle, and positive angle deflection scan frames, respectively, and S44, S45, and S46 correspond to the transmit and receive scan lines within the three angle frames.

[0059] The baseband raw echo signal frame within the user's region of interest includes the baseband raw signal frame S32 before tissue deformation, such as... Figure 6 S61, using Z f-1 It also includes the baseband original signal frame S36 after tissue deformation, such as... Figure 6 S62, using Z f This indicates that the frames before and after deformation contain multi-angle scan frames S31, such as... Figure 3 As shown in S33, S34, S35…;

[0060] Let its mathematical expression be Z. f (Angle(t), x, y) = I f (Angle, x, y) + Q f (Angle(t), x, y)*j,

[0061] Where I f (Angle(t), x, y) denotes the real part of the complex number, Q f (Angle(t), x, y) represents the imaginary part of the complex number, f is the display frame number, t is the same angle scan frame number, Angle is the deflection angle number, x is the horizontal line number, y is the vertical point number, and j represents the imaginary factor.

[0062] like Figure 1 As shown, S12 performs sparse sampling of the original baseband echo signals before and after deformation along the scanning line directions at various angles, such as... Figure 5 As shown, S51 corresponds to the baseband signal frame obtained before sparse sampling, which is set to RsZ. f-1 (Angle(t), x, y), S52 corresponds to the sparsely sampled baseband signal frame set as RsZ f (Angle(t), x, y), sparse sampling can interpolate and resample in the depth point direction S53, and can also interpolate and resample in the horizontal scan line direction S54.

[0063] As shown in step 2, the sparsely sampled baseband signal frame RsZ f-1 (Angle(t), x, y), RsZ f (Angle(t), x, y), such as Figure 1 S13 obtains the baseband echo sparse frame signal in the same direction before and after deformation, denoted as RsZ. f-1 (Angle(t), x, y), such as Figure 3S33 corresponds to A0, A1, A2…An, or S34 corresponds to B0, B1, B2…Bn, or S35 corresponds to C0, C1, C2…Cn;

[0064] After obtaining the set of frames at the same angle in step 3, such as Figure 1 S14 performs point-by-point Doppler velocity estimation on multiple frames of sparsely sampled baseband signals at different times and angles along the scan line and time direction. The Doppler velocity estimation formula can use an autocorrelation algorithm, where velocity V... f The formula for calculating (Angle, x, y) is as follows:

[0065]

[0066] in:

[0067]

[0068]

[0069] j: is the imaginary factor of the complex number;

[0070] T: represents the number of consecutive identical deflection angles;

[0071] Real{}:complex number RIZ f The real part of (Angle(t), x, y);

[0072] Imag{}:complex number RIZ f The imaginary part of (Angle(t), x, y);

[0073] atan(): Arctangent function;

[0074] PRT: Inter-frame time interval at the same angle;

[0075] Π is generally taken as 3.141;

[0076] The velocity V calculated in step 4 f After (Angle(rf), x, y), such as Figure 1 S16 calculates the displacement sequence frames at each angle based on the Doppler velocities at each angle. The calculation can be performed using a difference method, as shown in the following formula:

[0077] d f (Angle, x, y) = [V] f (Angle, x, y)-V f-1 (Angle, x, y)]*T*PRT

[0078] Where T and PRT have the same physical meaning as in step 4.

[0079] df (Angle, x, y): represents the displacement of the sampling point before and after deformation. It can be positive or negative. Positive indicates that the deformation is away from the probe, and negative indicates that it is towards the probe.

[0080] As shown in step 5, the angular displacement frames are calculated as follows: Figure 1 S15 according to the d f (Angle, x, y) calculates the precise displacement frame. A multi-angle displacement synthesis implementation method is as follows: Figure 7 As shown, S71 is a negative deflection sound beam frame, and S72 is a positive deflection sound beam frame. The black dot in the figure is the origin of the coordinate system. The angle between S71 and the sound beam direction is Angle1, and the amplitude value is d. f (Angle1, x, y), the angle between S72 and the direction of the sound beam is Angle2, and the amplitude value is d. f (Angle2, x, y) can be used to obtain the synthesized displacement value. One feasible formula is as follows:

[0081]

[0082] in:

[0083]

[0084]

[0085] exp: represents the exponential function e, j: represents the imaginary factor.

[0086] The displacement value of the current frame is represented as a vector, including the displacement value and direction.

[0087] The number of angles is not limited to two; it can be one, two, or more.

[0088] In medical color Doppler ultrasound systems, the detection of tissue stiffness mainly involves the precise calculation of tissue displacement.

[0089] This patent proposes a real-time, high-precision method for calculating tissue strain and displacement, which can meet the imaging requirements of various probes such as linear arrays, convex arrays, and phased arrays. This patent employs a cross-multi-angle scanning method and utilizes the Doppler principle to calculate tissue velocity and displacement, improving the accuracy of tissue displacement while minimizing data volume, and facilitating rapid transmission to the backend for processing and display.

[0090] This application has achieved the following beneficial effects:

[0091] 1. High real-time performance. Calculates displacement results quickly with minimal data volume;

[0092] 2. High precision. Multiple-directional scanning acquires Doppler frequency shift information and calculates displacement;

[0093] 3. The scanning control is simple and highly feasible, and it can be easily and quickly deployed in medical color ultrasound equipment.

[0094] This invention provides a device for improving the strain displacement accuracy of medical color Doppler ultrasound equipment, such as... Figure 2 As shown, it includes:

[0095] The original adjacent baseband signal frame acquisition module S21 is used to acquire the original baseband echo signal within the user's region of interest by front-end cross-transmission and reception of multi-angle ultrasonic carrier signals; the original baseband echo signal includes: the original baseband signal frames before and after tissue deformation.

[0096] The region of interest resampling module S22 is used to sparsely sample the original baseband echo signals before and after deformation along the scanning line direction at each angle, and obtain the original baseband echo signals in the same direction before and after deformation according to the time interval before and after deformation.

[0097] The same-angle velocity frame calculation module S23 is used to perform point-by-point Doppler velocity estimation of multiple frames of sparsely sampled baseband signals at different times with the same angle along the scan line and time direction.

[0098] The same angle displacement frame calculation module S24 is used to calculate the accurate displacement frame based on the displacement sequence frames of each angle.

[0099] The precise displacement acquisition module S25 is used to calculate and obtain displacement sequence frames at each angle based on the Doppler velocity at each angle.

[0100] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for improving the strain displacement accuracy of a medical color Doppler ultrasound device, characterized in that, include: S11. The front end cross-transmits and receives multi-angle ultrasonic carrier signals to obtain the original baseband echo signal within the user's region of interest. The baseband raw echo signal includes: baseband raw signal frames before and after tissue deformation; S12. Sparsely sample the baseband original echo signal before and after deformation along the scanning line direction at each angle. S13. Obtain the original baseband echo signals in the same direction before and after deformation based on the time interval before and after deformation. S14. Perform point-by-point Doppler velocity estimation on the multi-frame sparsely sampled baseband signals at different times and angles along the scan line and time direction. S15. Calculate the precise displacement frame based on the displacement sequence frames of each angle; S16. Calculate the displacement sequence frames of each angle based on the Doppler velocity at each angle.

2. The method for improving strain displacement accuracy in a medical color Doppler ultrasound device as described in claim 1, characterized in that, The front end cross-transmits and receives multi-angle ultrasonic carrier signals. Its cross-transmit and receive mode can act on the entire region of interest at once or on the region of interest multiple times. The required transmission and reception angles include positive or negative angles within zero angle.

3. The method for improving strain displacement accuracy in a medical color Doppler ultrasound device as described in claim 1, characterized in that, The baseband raw echo signal acquired by the user within the region of interest has equal and adjustable time intervals between adjacent frames, and similarly, the time intervals between each receiving line are also equal.

4. The method for improving strain displacement accuracy in a medical color Doppler ultrasound device as described in claim 1, characterized in that, Both the baseband raw signal frames before and after deformation contain multiple baseband raw signal frames with positive or negative angles within zero angle.

5. A method for improving strain displacement accuracy in a medical color Doppler ultrasound device as described in claim 1, characterized in that, Sparse sampling is the resampling of the original baseband signal frame based on the width, depth, and height of the region of interest.

6. The method for improving strain displacement accuracy in a medical color Doppler ultrasound device as described in claim 1, characterized in that, First, Doppler velocity is calculated for frame data at the same angle in the time direction. The Doppler velocity calculation method can be autocorrelation, cross-correlation, or other velocity calculation formulas. Then, the Doppler velocity in the depth direction is calculated point by point or jump point along the receiving line direction to obtain a velocity signal frame.

7. A method for improving strain displacement accuracy in a medical color Doppler ultrasound device as described in claim 1, characterized in that, Velocity frames at different angles form a velocity frame sequence. The displacement frame sequence is calculated from the velocity frame sequence and the inter-frame time interval. In the displacement frame sequence, the zero-angle displacement frame is used as the reference frame, and each positive or negative angle displacement frame is a dynamic frame. The reference frame is calibrated using each dynamic frame to obtain an accurate displacement frame.

8. A device for improving the strain displacement accuracy of a medical color Doppler ultrasound device, characterized in that, include: The original adjacent baseband signal frame acquisition module (S21) is used to acquire the original baseband echo signal within the user's region of interest by receiving multi-angle ultrasonic carrier signals through front-end cross-transmission. The baseband raw echo signal includes: baseband raw signal frames before and after tissue deformation; The region of interest resampling module (S22) is used to sparsely sample the original baseband echo signals before and after deformation along the scanning line direction at each angle, and obtain the original baseband echo signals in the same direction before and after deformation according to the time interval before and after deformation. The same-angle velocity frame calculation module (S23) is used to perform point-by-point Doppler velocity estimation on multiple frames of sparsely sampled baseband signals at different times with the same angle along the scan line and time direction; The same angle displacement frame calculation module (S24) is used to calculate the accurate displacement frame based on the displacement sequence frames of each angle. The precise displacement acquisition module (S25) is used to calculate and obtain the displacement sequence frames of each angle based on the Doppler velocity of each angle.

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