Method of remove blackground noise in short pulse excitation of ARFI

1. A method for operating an ultrasonic imaging system to eliminate background noises in shear waves, the method comprising:

transmitting a push pulse along a push pulse vector;

transmitting a first group of focus track pulses at a first plurality of locations having different distances in the same direction far away from the push pulse vector to capture background noise, wherein the track pulses are transmitted alternately in turn along the different distances in the same direction, wherein the plurality of locations comprises a first location, a second location, and a third location;

receiving a first group of interleaved focus echo signals in response to the first group of focus track pulses;

processing the first group of focus echo signals to determine a first group of tissue displacement information varying with time, where the first group of tissue displacement information comprises: first tissue displacement information corresponding to the first location; second tissue displacement information corresponding to the second location, and third tissue displacement information corresponding to the third location;

averaging the first tissue displacement information with the second tissue displacement information to generate first average tissue displacement information;

averaging the second tissue displacement information with the third tissue displacement information to generate second average tissue displacement information;

transmitting a second group of focus track pulses alternately in turn at a second plurality of locations, adjacent the push pulse vector, the second plurality of locations comprising a fourth location and a fifth location;

receiving a second group of focus echo signals in response to the second group of focus track pulses;

processing the second group of focus echo signals to determine a second group of tissue displacement information varying with time, where the second group of tissue displacement information comprises fourth tissue displacement information associated with the fourth location and fifth tissue displacement information associated with the fifth location;

subtracting the first average tissue displacement information from one of the fourth tissue displacement information and a third average tissue displacement information, calculated using the fourth tissue displacement information, to generate first displacement information excluding the background noise; and

subtracting the second average tissue displacement information from one of the fifth tissue displacement information and a fourth average tissue displacement information, calculated using the fifth tissue displacement information, to generate second displacement information excluding the background noise.

2. The method according to claim 1 , wherein the second plurality of locations further comprises a sixth location, and wherein the second group of tissue displacement information further comprises sixth tissue displacement information associated with the sixth location.

3. The method according to claim 2 , further comprising calculating the third average tissue displacement information by averaging the fourth tissue displacement information with the fifth tissue displacement information, and wherein the first displacement information excluding the background noise is generated by subtracting the first average tissue displacement information from the third average tissue displacement information.

4. The method according to claim 1 , wherein the second plurality of locations consists of the fourth location and the fifth location.

5. The method according to claim 4 , wherein the first displacement information excluding the background noise is generated by subtracting the first average tissue displacement information from the fourth tissue displacement information.

6. The method according to claim 5 , wherein the second displacement information excluding the background noise is generated by subtracting the second average tissue displacement information from the fifth tissue displacement information.

7. The method according to claim 1 , further comprising generating the fourth average tissue displacement information by averaging the fifth tissue displacement information with the sixth tissue displacement information, and wherein generating the second displacement information excluding the background noise comprises subtracting the second average tissue displacement information from the fourth average tissue displacement information.

8. The method according to claim 1 , further comprising calculating a shear wave velocity using the first displacement information excluding the background noise and the second displacement information excluding the background noise.

9. An ultrasonic imaging system, comprising:

an ultrasonic probe configured to:

transmit a push pulse along a push pulse vector;

transmitting a first group of focus track pulses at a first plurality of locations having different distances in the same direction far away from the push pulse vector to capture background noise, wherein the track pulses are transmitted alternately in turn along the different distances in the same direction, wherein the plurality of locations comprises a first location, a second location, and a third location;

receive a first group of interleaved focus echo signals in response to the first group of focus track pulses; and

a processor configured to:

process the first group of focus echo signals to determine a first group of tissue displacement information varying with time, where the first group of tissue displacement information comprises: first tissue displacement information corresponding to the first location; second tissue displacement information corresponding to the second location, and third tissue displacement information corresponding to the third location;

average the first tissue displacement information with the second tissue displacement information to generate first average tissue displacement information;

average the second tissue displacement information with the third tissue displacement information to generate second average tissue displacement information;

transmit a second group of focus track pulses alternately in turn at a second plurality of locations adjacent the push pulse vector, the second plurality of locations comprising a fourth location and a fifth location;

receive a second group of focus echo signals in response to the second group of focus track pulses;

process the second group of focus echo signals to determine a second group of tissue displacement information varying with time, where the second group of tissue displacement information comprises fourth tissue displacement information associated with the fourth location and fifth tissue displacement information associated with the fifth location;

subtract the first average tissue displacement information from one of the fourth tissue displacement information and a third average tissue displacement information, calculated using the fourth tissue displacement information, to generate first displacement information excluding the background noise; and

subtract the second average tissue displacement information from one of the fifth tissue displacement information and a fourth average tissue displacement information, calculated using the fifth tissue displacement information, to generate second displacement information excluding the background noise.

10. The ultrasonic imaging system according to claim 9 , wherein the second plurality of locations consists of the fourth location and the fifth location, and wherein the processor is configured to generate the first tissue displacement information excluding the background noise by subtracting the first average tissue displacement information from the fourth tissue displacement information.

11. The ultrasonic imaging system according to claim 10 , wherein the processor is configured to generated the second displacement information excluding the background noise by subtracting the second average tissue displacement information from the fifth tissue displacement information.

12. The ultrasonic imaging system according to claim 9 , wherein the second group of tissue displacement information comprises sixth tissue displacement information from a sixth location, wherein the processor is configured to calculate the third average tissue displacement information by averaging the fourth tissue displacement information with the fifth tissue displacement information, and wherein the processor is configured to generate the first displacement information excluding the background noise by subtracting the first average tissue displacement information from the third average tissue displacement information.

13. The ultrasonic imaging system according to claim 12 , wherein the processor is configured to generate fourth average tissue displacement information by averaging the fifth tissue displacement information with the sixth tissue displacement information, and wherein the processor is configured to generate the second displacement information excluding the background noise by subtracting the second average tissue displacement information from the fourth average tissue displacement information.

14. The ultrasonic imaging system according to claim 9 , wherein the processor is further configured to calculate a shear wave velocity using the first displacement information excluding the background noise and the second displacement information excluding the background noise.

15. The method according to claim 14 , wherein the processor is configured to calculate a Young's modulus according to the shear wave velocity.

16. The ultrasonic imaging system according to claim 9 , wherein the background noise comprises cardiac movement or respiratory movement.