Determination of shear wave characteristics

1. A method comprising:

applying a first ultrasound pulse to biological tissue to create shear waves in the biological tissue;

transmitting a second ultrasound pulse into the biological tissue;

receiving one or more ultrasound signals from the biological tissue generated in response to the second ultrasound pulse;

detecting the shear waves in the biological tissue based on the received one or more ultrasound signals;

determining a time to peak displacement of the shear waves at each of multiple positions in the biological tissue;

determining a square of shear wave propagation velocity based on the determined time to peak displacement of the shear waves at each of the multiple positions;

determining a color code representing the square of shear wave propagation velocity; and

displaying an image on a display monitor in which the biological tissue is represented by a color corresponding to the color code,

wherein determining the square of shear wave propagation velocity comprises:

calculating a square of the time to peak displacement of the shear waves at each of the multiple positions;

calculating a square of a distance of each of the multiple positions from an origin of the shear waves; and

calculating a regression line and a correlation coefficient between the square of the time to peak displacement and the square of the distance from the origin of the shear waves for each of the multiple positions;

determining a plurality of the multiple positions for which the correlation coefficient between the square of the time to peak displacement and the square of the distance from the origin of the shear waves for the plurality of the multiple positions is greater than a preset threshold;

calculating a second regression line between the square of the time to peak displacement and the square of the distance from the origin of the shear waves for each of the plurality of the multiple positions; and

determining a slope of the second regression line.

2. A method according to claim 1 , wherein determining the time to peak displacement of the shear waves comprises:

calculating a cross correlation, a sum of absolute differences (SAD), a sum of square differences (SSD), a sum of absolute cubic differences (SCD), or a sum of absolute power differences (SPD) between the received ultrasound signals.

3. A method according to claim 1 , wherein determining the time to peak displacement of the shear waves comprises:

calculating a color Doppler shift frequency, a color Doppler phase or a color Doppler velocity based on the I-Q signals of the received ultrasound signals.

4. A non-transitory medium storing computer-executable program code, the program code executable by a computing device to:

apply a first ultrasound pulse to biological tissue to create shear waves in the biological tissue;

transmit a second ultrasound pulse into the biological tissue;

receive one or more ultrasound signals from the biological tissue generated in response to the second ultrasound pulse;

detect the shear waves in the biological tissue based on the received one or more ultrasound signals;

determine a time to peak displacement of the shear waves at each of multiple positions in the biological tissue;

determine a square of shear wave propagation velocity based on the determined time to peak displacement of the shear waves at each of the multiple positions;

determine a color code representing the square of shear wave propagation velocity; and

display an image on a display monitor in which the biological tissue is represented by a color corresponding to the color code,

wherein determination of a square of shear wave propagation velocity based on the determined time to peak displacement of the shear waves at each of the multiple positions comprises:

calculation of a square of the time to peak displacement of the shear waves at each of the multiple positions;

calculation of a square of a distance of each of the multiple positions from an origin of the shear waves; and

calculation of a regression line and a correlation coefficient between the square of the time to peak displacement and the square of the distance from the origin of the shear waves for each of the multiple positions;

calculation of a square of the time to peak displacement of the shear waves at each of the multiple positions;

calculation of a square of a distance of each of the multiple positions from an origin of the shear waves; and

calculation of a regression line and a correlation coefficient between the square of the time to peak displacement and the square of the distance from the origin of the shear waves for each of the multiple positions.

5. A medium according to claim 4 , wherein the program code executable by a computing device to determine the time to peak displacement of the shear waves comprises program code executable by a computing device to:

calculate a cross correlation, a sum of absolute differences (SAD), a sum of square differences (SSD), a sum of absolute cubic differences (SCD), or a sum of absolute power differences (SPD) between the received ultrasound signals.

6. A medium according to claim 4 , wherein the program code executable by a computing device to determine the time to peak displacement of the shear waves comprises program code executable by a computing device to:

calculate a color Doppler shift frequency, a color Doppler phase or a color Doppler velocity based on the I-Q signals of the received ultrasound signals.

7. A system comprising:

a memory device;

a processor to execute computer-executable program code stored in the memory to cause the system to:

apply a first ultrasound pulse to biological tissue to create shear waves in the biological tissue;

transmit a second ultrasound pulse into the biological tissue;

receive one or more ultrasound signals from the biological tissue generated in response to the second ultrasound pulse;

detect the shear waves in the biological tissue based on the received one or more ultrasound signals;

determine a time to peak displacement of the shear waves at each of multiple positions in the biological tissue;

determine a square of shear wave propagation velocity based on the determined time to peak displacement of the shear waves at each of the multiple positions;

determine a color code representing the square of shear wave propagation velocity; and

display an image on a display monitor in which the biological tissue is represented by a color corresponding to the color code,

wherein determination of the square of shear wave propagation velocity comprises:

calculation of a square of the time to peak displacement of the shear waves at each of the multiple positions;

calculation of a square of a distance of each of the multiple positions from an origin of the shear waves;

calculation of a regression line and a correlation coefficient between the square of the time to peak displacement and the square of the distance from the origin of the shear waves for each of the multiple positions;

calculation of a square of the time to peak displacement of the shear waves at each of the multiple positions;

calculation of a square of a distance of each of the multiple positions from an origin of the shear waves; and

calculation of a regression line and a correlation coefficient between the square of the time to peak displacement and the square of the distance from the origin of the shear waves for each of the multiple positions.

8. A system according to claim 7 , wherein determination of the time to peak displacement of the shear waves comprises:

calculation of cross correlation, a sum of absolute differences (SAD), a sum of square differences (SSD), a sum of absolute cubic differences (SCD), or a sum of absolute power differences (SPD) between the received ultrasound signals.

9. A system according to claim 7 , wherein determination of the time to peak displacement of the shear waves comprises:

calculation of a color Doppler shift frequency, a color Doppler phase or a color Doppler velocity based on the I-Q signals of the received ultrasound signals.