WO2016029402A1

WO2016029402A1 - Shear wave imaging method and system

Info

Publication number: WO2016029402A1
Application number: PCT/CN2014/085391
Authority: WO
Inventors: 李双双; 樊睿
Original assignee: 深圳迈瑞生物医疗电子股份有限公司
Priority date: 2014-08-28
Filing date: 2014-08-28
Publication date: 2016-03-03
Also published as: CN110507360B; CN110507360A; CN110507359B; CN110507361B; CN110507361A; CN106572837A; CN110507359A; CN106572837B

Abstract

The present invention provides a shear wave imaging method. The method comprises the following steps: generating a shear wave in a tissue; pre-estimating the shear wave, sending tracking pulses many times at positions of the shear wave at different time points and receiving echo information of the tracking pulses; performing shear wave parameter calculation according to the echo information of the tracking pulses; and displaying a result of the shear wave parameter calculation in the form of an image. According to the shear wave imaging method and system provided in the present invention, a detection position of a shear wave is pre-estimated, so that shear wave detection can be accurately performed in a small range, and therefore detection energy is relatively concentrated and the signal-to-noise ratio of the detection is improved; the number of redundant detections is reduced, the detection process is accelerated, and the load of data processing is reduced. The present invention also provides a shear wave imaging system.

Description

Cutting ^ A image method and system

Technical field

The present invention relates to the field of ultrasonic imaging, and in particular to a shear wave imaging method and system. Background technique

Ultrasound elastography is one of the hotspots of clinical research in recent years. It mainly reflects the elasticity or softness of tissues. It has been applied more and more in the auxiliary detection of cancerous lesions, benign and malignant discrimination, and evaluation of prognosis. There is a prior art ultrasound elastography that uses shear waves for imaging, mainly by generating shear wave propagation inside the tissue and detecting its propagation parameters and imaging, thereby reflecting the difference in hardness between tissues.

This method has better stability and repeatability. However, in the application of this method, the shear wave generated inside the tissue is weak, and the propagation of the shear wave in the tissue is a transient process. When the shear wave propagates for a certain time and a certain distance, it will attenuate and disappear, so it must be The extraction of shear wave information in a fast and large area over a period of time requires high requirements for the extraction of shear waves, and the data processing load of the extraction system for shear wave extraction is large and the precision is low. Summary of the invention

A shear wave imaging method and system are provided to improve the detection signal to noise ratio, reduce the number of redundant detections, and speed up the detection process.

A shear wave imaging method, comprising the following steps,

Producing shear waves inside the tissue;

Estimating the position of the shear wave at different times, transmitting a plurality of tracking pulses corresponding to the shear wave at different times and receiving echo information of the tracking pulse;

Performing shear wave parameter calculation according to echo information of the tracking pulse;

Imaging shows the results of the shear wave parameter calculation.

Further, when the shear wave is estimated, corresponding to the shear wave transmitting the tracking pulse at different times and receiving the echo information of the tracking pulse, the following steps are further included,

Estimating the propagation velocity of the shear wave within the target tissue;

Estimating the shear wave at each moment according to the propagation speed of the shear wave in the target tissue The estimated position of the shear wave in the target tissue;

The tracking pulses are transmitted to the respective shear wave estimation positions at the respective times, and the echo information of the respective tracking pulses is received.

Further, when the shear wave estimation position of the shear wave is obtained at each moment, the distance between the shear wave and the wave source is satisfied:

d _k = (t _k - t ₀ ) *

Wherein, ^ is any time after the generation of the shear wave, and ^ is the initial propagation time of the shear wave, which is the average velocity of the shear wave propagating in the target tissue.

Further, the moving distance of the shear wave detecting position between two adjacent detecting moments is less than or equal to c _h At , and the detecting width of the shear wave is greater than or equal to each of the detected shear waves. The speed varies from to, and At is the time interval between two adjacent detection times.

Further, when calculating the shear wave parameter based on the echo information of the tracking pulse, performing at least one of a propagation distance of the shear wave, a propagation speed of the shear wave, and a Young's modulus of the target tissue Calculation.

Further, when performing shear wave parameter calculation according to the echo information of the tracking pulse, the method further includes the following steps:

Set reference information;

Correlation correlation is performed between the echo information of the tracking pulse at different times in each position in the target area and the reference information corresponding to the position, and the particle displacement data at different times at the position is obtained.

Further, when the reference information is set, the echo information of the tracking pulse at a certain time is selected as the reference information or the reference pulse is transmitted before the shear wave propagation, and the echo information of the reference pulse is used as the reference echo information.

Further, when the shear wave parameter is calculated according to the echo information of the tracking pulse, the propagation speed of the shear wave satisfies the following formula:

Where C represents the propagation velocity, which can be regarded as longitudinal displacement data, or can be calculated using longitudinal velocity data, where X represents the lateral coordinate and z represents the longitudinal coordinate.

Further, when the imaging shows the crusting calculated by the shear wave parameter, a propagation velocity profile is formed, At least one of a Young's modulus parameter map, a shear modulus parameter map, a propagation distance parameter map for a certain period of time, and an average velocity value parameter map within the target region.

A shear wave imaging system includes an ultrasound probe, a control module, a signal processing module, a calculation module, and a display system. The ultrasound probe is provided with a transceiver module, a transceiver module, a signal processing module, a calculation module, and a display of the ultrasound probe. The system is connected in sequence, the control module is connected to the transceiver module, and the transceiver module is configured to transmit a tracking pulse according to a shear wave estimation position, and receive echo information of the tracking pulse and the reference pulse;

The control module is configured to control the transceiver module to transmit a tracking pulse;

The signal processing module is configured to perform signal preprocessing on the echo information;

The calculation module is configured to estimate a shear wave estimation position of the shear wave at different times, and process and calculate a signal output by the signal processing module;

The display system is configured to perform image display on a shear wave parameter calculation result generated by the calculation module.

Further, the calculation module includes

And an estimating unit configured to estimate a shear wave estimated position of the shear wave at each moment according to an average length of the shear wave propagation time and a shear wave propagation in the target tissue.

A data calculation unit for calculating a propagation parameter of the shear wave.

The shear wave imaging method and system provided by the invention pre-estimate the detection position of the shear wave, so that the detection of the shear wave can be performed in a small range and accurately, so that the detection energy is relatively concentrated, and the detection signal-to-noise ratio is improved. At the same time, it reduces the number of redundant detections, speeds up the detection process, and reduces the data processing burden. DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only It is a certain embodiment of the present invention, and other drawings can be obtained from those skilled in the art without any creative work.

1 is a schematic flow chart of a shear wave imaging method provided by the present invention;

2 to FIG. 5 are schematic diagrams showing pulse sequences for emitting different acoustic radiation forces in the shear wave imaging method of the present invention; 6 is a schematic diagram showing the change of the shear wave detecting position with time according to the shear wave imaging method of the present invention; FIG. 7 to FIG. 8 are schematic diagrams showing the emission deflection angle of the deflection angle of the different tracking pulses in the present invention;

9 is a schematic view showing the configuration of a shear wave imaging system provided by the present invention. detailed description

BRIEF DESCRIPTION OF THE DRAWINGS The technical solutions in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative work are within the scope of the present invention.

Referring to FIG. 1 , a preferred embodiment of the present invention provides a shear wave imaging method for predicting a detection position of a shear wave in advance, so that the detection of the shear wave can be performed in a small range and accurately, so that the detection energy is relatively concentrated. Improve the detection signal to noise ratio. At the same time, the number of redundant detections is reduced, the detection process is accelerated, and the data processing burden is reduced.

The shear wave imaging method of the present invention comprises the following steps:

Step S101, generating a shear wave inside the tissue. In this step, various methods can be used to generate shear waves inside the tissue, such as external waves vibrating inside the tissue to generate shear waves, and also by transmitting acoustic radiation force pulses to the inside of the tissue (ARFI, acoustic radiation Force impulse ) and the like generate shear waves inside the tissue. Wherein, the acoustic radiation force pulse may or may not be in focus.

It can be understood that the shear wave itself generated by the acoustic radiation force pulse has a small amplitude, and since the shear wave is rapidly attenuated with the propagation, a series of acoustic radiation force pulses can be emitted to increase the shear wave intensity. , or widening the propagation range of the shear wave, or changing the characteristics of the shear wave waveform has improved the detection sensitivity, etc., thereby avoiding imaging due to the attenuation of the shear wave.

As shown in Fig. 2, multiple focus pulses can be continuously transmitted to the same position to increase the intensity of the generated shear wave. As shown in FIGS. 3 and 4, the position of the longitudinal direction of the focus pulse (in the direction of the focus emission) and the direction of the lateral direction (the direction perpendicular to the focus emission) can be changed to widen the propagation range of the shear wave and make the cut The cut wave propagates in a specific direction. As shown in Fig. 5, pulses can be simultaneously transmitted at different lateral positions to superimpose two shear wave waveforms arriving at different times for convenient detection.

Step S102, estimating a position of the shear wave at different times, corresponding to the shear wave being different The position of the moment transmits a plurality of tracking pulses and receives echo information of the tracking pulses.

The step S102 further includes the following steps:

In step S1021, the propagation speed of the shear wave in the target tissue is estimated.

After the shear wave is generated, it begins to propagate in the tissue, and its propagation speed is different depending on the elastic properties of the tissue. In order to estimate the chasing shear wave, it is necessary to estimate an average speed according to the target organization and estimate the possible speed variation range to c _A . The average speed and range can refer to existing academic measurement data, or measurement experience, etc., depending on the situation. Pre-designated. For example, suppose the average propagation velocity of the shear wave in the target tissue is about 2m/s, the possible range of variation is l~4m/s, etc., or the average propagation velocity is lm/s, and the possible variation range is 0.5~ 2m/s and so on.

Step S1022: Estimating the position of the shear wave in the target tissue at each time according to the propagation speed of the shear wave in the target tissue, and acquiring the shear wave estimate of the shear wave at each moment. position.

At different times after the shear wave is generated, it is assumed that the shear wave starts to propagate at t. , you can estimate the distance from the source of the wave source to satisfy the following relationship:

d _k = (t _k - t ₀ ) * c

Assuming that the time interval between two adjacent detection times is At, that is, satisfying: At = ^ - t _k _ _x , the propagation range Δ 〜 M _{h of the} shear wave between the two detection times can be estimated, which satisfies: M _A = c _h At Therefore, the moving distance of the shear wave detecting position between two adjacent detecting moments is less than or equal to Δ, and the estimated positioning is advanced when the shear wave propagation is too slow, and the detection width of the shear wave is detected each time. greater than or equal to _{Μ Λ - Δ = at (c} h - c t), in order to ensure that each of the estimated positioning time a shear wave can contain all possible positions.

Step S1021: Send a tracking pulse to the corresponding shear wave estimation position at each time, and receive echo information of each tracking pulse.

As shown in Fig. 6, starting from the start of the shear wave propagation, the system transmits the tracking pulse at intervals to continuously detect, and each detection maintains a certain detected lateral beamwidth, that is, simultaneously recovers a certain width of echo information, echo information. Including the information of each of the above-mentioned lateral positions of a certain width, the interval of the lateral positions may not be too large to ensure a certain lateral resolution. At the same time, the beam center remains less than Δ between adjacent detections. The moving distance, or if At is small, causes Δ to be too small, it is also equivalent to the moving distance at which the beam center distance remains less than every n detection times. Of course, the system can start detecting from any time or start from a distance from the shear wave source. It is only necessary to estimate the possible position of the shear wave at the current position or the current time according to the average propagation speed. The shear wave is transmitted to this position and left to change the center position of each test.

Since each detection must maintain a certain lateral beamwidth, and the lateral line spacing cannot be too large to ensure a certain lateral resolution, the system may be required to have ultra-wide beam combining capability, that is, to recover echo information of multiple lateral positions at the same time. Ability, as shown in Figure 7 and Figure 8. The number of beams is, for example, 1 to 1024, and the system adjusts according to requirements, such as 4 beams, 16 beams, 32 beams, 64 beams, 96 beams, 128 beams, and so on. The wider the beam, the weaker the focus of the transmitted sound field, and the more uniform the lateral distribution of the sound field energy, the less concentrated it will also result in a lower signal-to-noise ratio for each detected position in the beam. In order to improve the quality of the detection, the same center position can be transmitted multiple times in succession, each time the angle of the beam is different, and then the echo signals of different angles are combined to increase the signal-to-noise ratio. The number of angles and the angle of deflection are adjusted by the system according to actual needs, such as using three angles and deflecting -5. , 0. , 5. Wait.

Step S103, performing shear wave parameter calculation according to the echo information of the tracking pulse. According to the echo information of the tracking pulse, various parameters such as propagation distance, propagation speed, Young's modulus, and the like can be calculated.

In this step, the echo information of the tracking pulse at each moment can be integrated to obtain the echo information of the shear wave at various positions of the target tissue during the propagation process, and the shear wave is just here. Pass the corresponding position for a short period of time.

The step S103 further includes the following steps:

Step S1031: Obtain reference information; It can be understood that the reference information can be selected according to needs. For example, the echo information of the tracking pulse at a certain moment in the corresponding position is selected as the reference information. It is also possible to transmit a reference pulse before the shear wave propagation and use the echo information of the reference pulse as reference echo information. The reference is required for cross-correlation comparison with tracking pulses that are chasing the shear wave.

Step S1032: Correlate the echo information of the tracking pulse at different times in each position in the target area with the reference information corresponding to the position, and obtain the particle displacement data at different times at the position. Further, a displacement-time curve at the position can be formed, during which the shear wave experiences the entire process of approaching, reaching, and leaving the position, and a peak appears in the corresponding curve. As shown in Figure 5, by For the estimated pursuit detection, a corresponding small displacement-time curve can be obtained for each lateral position, but the time corresponding to the curve is different, and the moments corresponding to the adjacent positions may partially overlap. The position of the peak on the displacement-time curve corresponds to the moment when the shear wave reaches the position.

There are various calculation methods for the propagation speed of the shear wave. For example, for the displacement-time curve corresponding to two different lateral positions on the same depth, the cross-correlation comparison can be performed to obtain the corresponding time difference between the two lateral positions. Corresponds to the shear wave propagation time between these two lateral positions. The ratio of the distance between the lateral positions to the propagation time is the propagation velocity between the two horizontal positions.

For example, for a certain position, the displacement data of each lateral position corresponding to the two moments at which the shear wave reaches the position is taken out, and the displacement-transverse position curve of the two moments is formed, and the cross-correlation comparison of the two curves can obtain two The difference in lateral position between the moments, which corresponds to the propagation distance of the shear wave between the two moments. The ratio of the propagation distance to the time difference between the two moments is the propagation velocity near the location.

For example, the approximate calculation formula can be derived by directly using the wave propagation equation as follows:

Where c is the propagation velocity, which can be regarded as longitudinal displacement data, or can be calculated using longitudinal velocity data, where X represents the lateral coordinate and Z represents the longitudinal coordinate. It is also possible to transform the above formula into the frequency domain for calculation.

Under certain conditions, the propagation velocity of the shear wave has a nearly fixed relationship with the tissue hardness:

E = 3pc ² where P is the tissue density and represents the Young's modulus value of the tissue. Under certain conditions, the larger the Young's modulus, the greater the tissue hardness.

Further, from the value of the propagation velocity of the shear wave at each position, the shear modulus, the propagation distance in a certain fixed period, the average propagation velocity in the target region, and the like can be further calculated.

Step S104, imaging displays the result of the shear wave parameter calculation.

After obtaining the final propagation velocity data, it can be displayed on the image to form a propagation velocity distribution map. The difference in propagation velocity between each position on the graph directly reflects the difference in hardness. Of course, other parameter maps can also be displayed, such as Young's modulus parameter map, shear modulus parameter map, and propagation distance parameters for a certain period of time. Figure, the average speed value parameter map in the target area, and so on. The above parameters can be displayed as a movie map, a plane or a spatial distribution map, a parameter value, a graph, etc., or may be grayscale or color coded, or may be superimposed or merged with other pattern diagrams such as an anatomical map. Show together.

As shown in FIG. 9 , the present invention further provides a shear wave imaging system, including an ultrasound probe 11 , a control module 12 , a signal processing module 13 , a calculation module 15 , and a display system 17 . The ultrasound probe 11 is provided with a transceiver module 110 . The transceiver module 110, the signal processing module 13, the calculation module 15, and the display system 17 of the ultrasound probe 11 are sequentially connected, and the control module 12 is connected to the transceiver module 110. among them:

The transceiver module 110 is configured to transmit a tracking pulse and receive echo data of the tracking pulse and the reference pulse.

The control module 12 is configured to control the transceiver module 110 to transmit a tracking pulse. In actual use, the control module 12 transmits a specific ultrasound sequence formed by the tracking pulses according to a preset time interval, thereby facilitating the pursuit of the shear wave and for the transceiver module 110 of the ultrasound probe 11 to receive the corresponding echo data.

The signal processing module 13 is configured to perform signal preprocessing on the echo data, thereby facilitating the calculation module 15 to perform subsequent calculations. The signal preprocessing may include beamforming processing, and may also include, for example, signal amplification, analog to digital conversion, and orthogonality. Decomposition and so on.

The calculation module 15 is for estimating the position of the shear wave at different times and for processing and calculating the signal used for the beam synthesis output.

In this embodiment, the calculating module 15 includes:

The estimating unit 151 is configured to estimate the shear wave estimated position of the shear wave at each moment according to the propagation duration of the shear wave and the average speed of the shear wave propagated in the target tissue.

The data calculation unit 153 is configured to calculate a propagation parameter of the shear wave.

The display system 17 is for performing image display on the shear wave parameter calculation result generated by the calculation module 15.

It can be understood that the physical setting positions of the ultrasound probe 11, the control module 12, the signal processing module 13, the calculation module 15, and the display system 17 can be adjusted as needed, such as the ultrasound probe 11, the control module 12, and the signal processing. The module 13, the calculation module 15 and the display system 17 are uniformly arranged in the same casing to realize an integrated setting; the split settings can also be used, and wired or wirelessly connected for data communication. The shear wave imaging method and system provided by the invention generate shear waves inside the tissue, and predict and pursue the propagation process of the shear wave in a period of time, and the pursuit position changes continuously with the propagation, so each moment It is only necessary to obtain the propagation position information in a small and small range, and then integrate the obtained information to calculate the elasticity-related parameters such as the shear wave wavefront movie map, propagation distance, and propagation speed in the target area, and finally image to reflect between different tissues. The difference in elasticity. The shear wave imaging method of the present invention predicts the detection position of the shear wave in advance, so that the detection of the shear wave can be performed in a small range and accurately, so that the detection energy is relatively concentrated, and the detection signal-to-noise ratio is improved. At the same time, the number of redundant detections is reduced, the detection process is accelerated, and the data processing load of the system is reduced.

The above is only a preferred embodiment of the present invention, and of course, the scope of the present invention is not limited thereto, and those skilled in the art can understand all or part of the process of implementing the above embodiments, and according to the present invention. The equivalent changes required are still within the scope of the invention.

Claims

Rights request

A shear wave imaging method, comprising: the following steps,

Producing shear waves inside the tissue;

Imaging shows the results of the shear wave parameter calculation.

2. The shear wave imaging method according to claim 1, wherein

When the shear wave is estimated, corresponding to the shear wave transmitting the tracking pulse at different times and receiving the echo information of the tracking pulse, the following steps are further included,

Estimating the propagation velocity of the shear wave within the target tissue;

Estimating a shear wave estimated position of the shear wave in the target tissue at each time according to the propagation speed of the shear wave in the target tissue;

The shear wave imaging method according to claim 2, wherein when the shear wave estimated position of the shear wave is obtained at each moment, the position distance of the shear wave source is satisfied : d _k = (t _k - t ₀ ) * c

Wherein, at any time after the generation of the shear wave, the ^ is the initial propagation time of the shear wave, and is the average velocity of the shear wave propagating in the target tissue.

4. The shear wave imaging method according to claim 2, wherein a moving distance of the shear wave detecting position between two adjacent detecting times is less than or equal to _c3⁄4 At, and the shear wave is detected each time. The detection width is greater than or equal to At(c _A - ), wherein the estimated shear wave velocity varies from ^c " , At is the time interval between two adjacent detection times.

The shear wave imaging method according to claim 1, wherein when the shear wave parameter is calculated based on the echo information of the tracking pulse, the propagation distance of the shear wave and the shear wave are At least one of the propagation speed and the Young's modulus of the target tissue is calculated.

6. The shear wave imaging method according to claim 1, wherein: according to said tracking pulse When the echo information of the punch is calculated by the shear wave parameter, the following steps are further included:

Set reference information;

7. The shear wave imaging method according to claim 6, wherein when the reference information is set, the echo information of the tracking pulse at a certain time is selected as the reference information or the reference pulse is transmitted before the shear wave propagates. The echo information of the reference pulse is used as reference echo information.

The shear wave imaging method according to claim 1, wherein when the shear wave parameter is calculated based on the echo information of the tracking pulse, the propagation speed of the shear wave satisfies the following formula:

Where c is the propagation velocity, which can be regarded as longitudinal displacement data, or can be calculated using longitudinal velocity data, where X represents the lateral coordinate and Z represents the longitudinal coordinate.

9. The shear wave imaging method according to claim 1, wherein when the imaging results of the shear wave parameter calculation are performed, a propagation velocity profile, a Young's modulus parameter map, and a shear modulus parameter are formed. The graph, the propagation distance parameter map in a certain period of time, and at least one of the average speed value parameter maps in the target area.

A shear wave imaging system, comprising: an ultrasonic probe, a control module, a signal processing module, a calculation module, and a display system, wherein the ultrasonic probe is provided with a transceiver module, the transceiver module of the ultrasonic probe, and signal processing The module, the computing module, and the display system are sequentially connected, and the control module is connected to the transceiver module.

The transceiver module is configured to transmit a tracking pulse according to a shear wave estimated position, and receive echo information of the tracking pulse and the reference pulse;

The display system is configured to perform image display on the shear wave parameter calculation result generated by the calculation module.

11. The shear wave imaging system of claim 10, wherein the calculation module comprises

The estimating unit is configured to calculate a propagation parameter of the shear wave according to a data calculation unit that is based on a propagation time of the shear wave and a shear wave propagated in the target tissue.