Method and device for detecting elasticity of viscous elastic medium

1. A method for detecting an elasticity of a viscoelastic medium, comprising:

detecting a pressure applied to the viscoelastic medium by an ultrasonic transducer probe;

in response to the pressure satisfying a predetermined condition, triggering detection of the elasticity of the viscoelastic medium according to the following steps:

driving the ultrasonic transducer probe with a low-frequency vibration by a vibrator so as to produce an elastic wave in the viscoelastic medium;

producing an ultrasonic wave by the ultrasonic transducer probe, and transmitting the ultrasonic wave to the viscoelastic medium;

collecting an ultrasonic echo; and

calculating an elastic parameter of the viscoelastic medium according to the collected ultrasonic echo,

wherein the ultrasonic echo is collected when the elastic wave is propagated in the viscoelastic medium and the ultrasonic transducer probe stops or almost stops vibrating, wherein, a serial number N select of a collected ultrasonic echo satisfying:

N select ≥ceiling(( T+ΔT )× F high ),

where ceiling(.) is a ceiling rounding function, F high is a pulse repetition frequency of transmitting an ultrasonic signal and is within a range from 100 Hz to 100000 Hz, T is the duration of the vibration, the ultrasonic transducer probe stops or almost stops vibrating after the vibration starts for a period of T+ΔT,

when the elastic wave is propagated in the viscoelastic medium, the serial number N select of the collected ultrasonic echo satisfying:

N select ≤ceiling(( D 1 /V s1 +T )× F high );

where, D 1 is a thickness of the viscoelastic medium, V s1 is a lower limit of a propagation velocity of the elastic wave in the viscoelastic medium determined according to an estimated hardness range and an estimated density of the viscoelastic medium;

when ΔT is less than D 1 /V s1 , by combining above two formulae, N select satisfying:

ceiling(( T+ΔT )× F high )≤ N select ≤ceiling(( D 1 /V+T )× F high ); and

when ΔT is not less than D 1 /V s1 , an elastic intermediate medium with a thickness of D 2 and a first hardness is added between the ultrasonic transducer probe and the viscoelastic medium so that ΔT<D 1 /V s1 +D 2 /V s2 , where V s2 is a propagation velocity of the elastic wave in the elastic intermediate medium, then the serial number N select of the collected ultrasonic echo satisfying:

ceiling(( T+ΔT )× F high )≤ N select ≤ceiling(( D 2 /V s2 /D 1 /V s1 +T )× F high ).

2. The method according to claim 1 , wherein

detecting an average pressure sensed on the viscoelastic medium by a pressure sensor array disposed on the ultrasonic transducer probe;

in response to the average pressure satisfying a predetermined condition, triggering detection of the elasticity of the viscoelastic medium.

3. The method according to claim 2 , further comprising:

detecting a pressure difference sensed on the viscoelastic medium by the pressure sensor array disposed on the ultrasonic transducer probe, and calculating a verticality parameter based on the average pressure and the pressure difference;

in response to each of the average pressure and the verticality parameter satisfying a predetermined condition, triggering detecting the elasticity of the viscoelastic medium.

4. The method according to claim 1 , before driving the ultrasonic transducer probe with the low-frequency vibration by the vibrator, further comprising:

acquiring with an ultrasonic imaging probe an ultrasonic image of the viscoelastic medium;

determining an area to detect the elastic parameter of the viscoelastic medium according to the ultrasonic image.

5. The method according to claim 4 , wherein,

the ultrasonic image is a M-mode ultrasonograph, a two-dimensional ultrasonic image or three-dimensional ultrasonic image.

6. A device for detecting an elasticity of a viscoelastic medium, comprising:

a vibrator producing a low-frequency vibration;

an ultrasonic transducer probe driven by the vibrator with the low-frequency vibration so as to produce an elastic wave in the viscoelastic medium;

a pressure sensor array, disposed on the ultrasonic transducer probe and configured to detect a pressure applied to the viscoelastic medium by the ultrasonic transducer probe; and

a control apparatus connected with the ultrasonic transducer probe, the vibrator and the pressure sensor array respectively, and configured to trigger detection of the elasticity of the viscoelastic medium in response to the pressure applied to the viscoelastic medium satisfying a predetermined condition,

wherein the ultrasonic transducer probe is configured to transmit an ultrasonic wave to the viscoelastic medium and to collect an ultrasonic echo returned from the viscoelastic medium after the control apparatus triggers detection of the elasticity of the viscoelastic medium, and the control apparatus is further configured to calculate an elastic parameter of the viscoelastic medium according to the collected ultrasonic echo,

wherein the control apparatus is configured to control the ultrasonic transducer probe to collect the ultrasonic echo when the elastic wave is propagated in the viscoelastic medium and the ultrasonic transducer probe stops or almost stops vibrating,

wherein a serial number N select of a collected ultrasonic echo satisfying:

N select ≥ceiling(( T+ΔT )× F high )

where ceiling(.) is a ceiling rounding function, F high is a pulse repetition frequency of transmitting an ultrasonic signal and is within a range from 100 Hz to 100000 Hz, T is the duration of the vibration, the ultrasonic transducer probe stops or almost stops vibrating after the vibration starts for a period of T+ΔT;

when the elastic wave is propagated in the viscoelastic medium, the serial number N select of the collected ultrasonic echo satisfying:

N select ≤ceiling(( D 1 /V s1 +T )× F high )

where, D 1 is a thickness of the viscoelastic medium, V s1 is a lower limit of a propagation velocity of the elastic wave in the viscoelastic medium determined according to an estimated hardness range and an estimated density of the viscoelastic medium;

when ΔT is less than D 1 /V s1 , by combining above two formulae, N select satisfying:

ceiling(( T+ΔT )× F high )≤ N select ≤ceiling(( D 1 /V s1 +T )× F high ); and

when ΔT is not less than D 1 /V s1 an elastic intermediate medium with a thickness of D 2 and a first hardness is added between the ultrasonic transducer probe and the viscoelastic medium so that ΔT<D 1 /V s1 +D 2 /V s2 , where V s2 is a propagation velocity of the elastic wave in the elastic intermediate medium, then the serial number N select of the collected ultrasonic echo satisfying:

ceiling(( T+ΔT )× F high )≤ N select ≤ceiling(( D 2 /V s2 +D 1 /V s1 +T )× F high ).

7. The device according to claim 6 , wherein the control apparatus comprises one of a computer, a microprocessor and a microcontroller, as well as an ultrasonic transmitting and receiving circuit connected with the one of the computer, the microprocessor and the microcontroller through a communication interface.

8. The device according to claim 6 , wherein the control apparatus comprises a triggering key implemented by a hardware or a software for starting to detect the elastic parameter of the viscoelastic medium.

9. The device according to claim 6 , wherein the control apparatus further comprises a pressure signal collecting circuit connected with one of a computer, a microprocessor and a microcontroller through a communication interface.

10. The device according to claim 6 , wherein the control apparatus is configured to detect an average pressure sensed on the viscoelastic medium according to the pressure detected by the pressure sensor array, and to trigger detecting the elasticity of the viscoelastic medium in response to the average pressure parameter satisfying a predetermined condition.

11. The device according to claim 10 , wherein the control apparatus is further configured to detect a pressure difference sensed on the viscoelastic medium according to the pressure detected by the pressure sensor array, to calculate a verticality parameter based on the pressure difference and the average pressure, and to trigger detecting the elasticity of the viscoelastic medium in response to each of the average pressure and the verticality parameter satisfying a predetermined condition.

12. The device according to claim 6 , further comprising an ultrasonic diagnostic equipment connected with the control apparatus for acquiring an ultrasonic image of the viscoelastic medium via an ultrasonic imaging probe thereof,

wherein the control apparatus is further configured to determine an area to detect the elastic parameter of the viscoelastic medium according to the ultrasonic image.

13. The device according to claim 12 , wherein,

the ultrasonic image is a M-mode ultrasonograph, a two-dimensional ultrasonic image or three-dimensional ultrasonic image.

14. The device according to claim 6 , further comprising a state indicating device for indicating a current working state of the device.

15. The device according to claim 6 , further comprising a mechanical arm for supporting an ultrasonic probe consisting of the ultrasonic transducer probe and the vibrator.