Method and ultrasound system for shear wave elasticity imaging

Method for two-dimensional shear wave elastography imaging comprising:

• a) acquiring B-mode ultrasound images of a target region in a body under examination;
• b) selecting a region of interest inside the said B-mode image;
• c) transmitting a shear wave excitation pulse focalized on an excitation region;
• d) measuring displacements of a certain number of tracking focal points at different depths positions along each one of a predefined number of laterally staggered tracking lines within the selected region of interest;
• e) determining elasticity parameters of regions between at least two of the tracking focal points at the same depth and on at least two adjacent tracking lines as a function of the displacements caused by the shear wave at the tracking focal points;
• f) modifying the appearance of at least one pixel of the B-mode image inside the said regions relatively to the grey-scale B-mode image as a function of at least one of the elasticity parameters determined for the said regions;
• g) displaying the at least one pixel having the modified appearance at the corresponding pixel of the B-mode image;
• wherein step f) comprises determining pixel appearance in the HSL (Hue, Saturation, Lightness) or the HSV (Hue, Saturation, Value) or the HSI (Hue, Saturation, Intensity) color three space coordinates;
• and
• wherein the pixel appearance is set by encoding the B-mode intensity value into a first coordinate, the elasticity or velocity parameter into a second coordinate and a fixed value into a third coordinate of the color three space coordinates.

Method for two-dimensional shear wave elastography imaging comprising:

• a) acquiring B-mode ultrasound images of a target region in a body under examination;
• b) selecting a region of interest inside the said B-mode image;
• c) transmitting a shear wave excitation pulse focalized on an excitation region;
• d) measuring displacements of a certain number of tracking focal points at different depths positions along each one of a predefined number of laterally staggered tracking lines within the selected region of interest;
• e) determining elasticity parameters of the regions between at least two of the tracking focal points at the same depth and on at least two adjacent tracking lines as a function of the displacements caused by the shear wave at the said tracking focal points;
• f) determining the statistical reliability of the velocity or of the elasticity parameter as calculated;
• g) modifying the appearance of at least one pixel of the B-mode image inside the said regions relatively to the grey-scale B-mode image as a function of the elasticity parameter and the statistical reliability of the elasticity parameter;
• i) displaying the at least one pixel having the modified appearance at the corresponding pixel of the B-mode image.

An ultrasound system for shear wave elasticity imaging (SWEI) comprising:

• an ultrasound probe;
• an ultrasound transmit wave generator and an ultrasound transmit beamformer to provide transmit signals to the ultrasound probe;
• an ultrasound receive-beamformer;
• ultrasound receive signals processing unit for generating ultrasound image data from received echo signals;
• a shear wave excitation pulse generator and a shear wave beamformer;
• an image display;
• a memory storing program instructions;
• and
• at least one processor that executes the program instructions to:
• a) acquire B-mode ultrasound images of a target region in a body under examination;
• b) select a region of interest inside the said B-mode image;
• c) transmit a shear wave excitation pulse focalized on an excitation region;
• d) measure displacements of a certain number of tracking focal points at different depths positions along each one of a predefined number of laterally staggered tracking lines within the selected region of interest;
• e) determine elasticity parameters of regions between at least two of the tracking focal points at the same depth and on at least two adjacent tracking lines as a function of the displacements caused by the shear wave at the tracking focal points;
• f) modify the appearance of at least one pixel of the B-mode image inside the said regions relatively to the grey-scale B-mode image as a function of at least one of the elasticity parameters determined for the said regions;
• g) display the at least one pixel having the modified appearance at the corresponding pixel of the B-mode image;
• wherein a statistical reliability of a calculated velocity or of the elasticity parameter determined as a function of the measured shear wave effects at the different tracking points is determined for the elasticity parameter of each sub-region of the selected region of interest and the pixel appearance is modified in order to visualize also the reliability of the elasticity parameter determined for the corresponding sub-region;
• and
• wherein the values of the B-mode image, the elasticity or velocity parameter and the statistical reliability of elasticity or velocity parameter are visualized as a single image by encoding such values in the HSL (Hue, Saturation, Lightness) or the HSV (Hue, Saturation, Value) or the HSI (Hue, Saturation, Intensity) color space.

An ultrasound system for shear wave elasticity imaging (SWEI) comprising:

• an ultrasound probe;
• an ultrasound transmit wave generator and an ultrasound transmit beamformer to provide transmit signals to the ultrasound probe;
• an ultrasound receive-beamformer;
• ultrasound receive signals processing unit for generating ultrasound image data from received echo signals;
• a shear wave excitation pulse generator and a shear wave beamformer;
• an image display;
• a memory storing program instructions;
• and
• at least one processor that executes the program instructions to:
• a) acquire B-mode ultrasound images of a target region in a body under examination;
• b) select a region of interest inside the said B-mode image;
• c) transmit a shear wave excitation pulse focalized on an excitation region;
• d) measure displacements of a certain number of tracking focal points at different depths positions along each one of a predefined number of laterally staggered tracking lines within the selected region of interest;
• e) determine elasticity parameters of regions between at least two of the tracking focal points at the same depth and on at least two adjacent tracking lines as a function of the displacements caused by the shear wave at the tracking focal points;
• f) modify the appearance of at least one pixel of the B-mode image inside the said regions relatively to the grey-scale B-mode image as a function of at least one of the elasticity parameters determined for the said regions;
• g) display the at least one pixel having the modified appearance at the corresponding pixel of the B-mode image;
• wherein step f) comprises determining pixel appearance in the HSL (Hue, Saturation, Lightness) or the HSV (Hue, Saturation, Value) or the HSI (Hue, Saturation, Intensity) color three space coordinates;
• and
• wherein the pixel appearance is set by encoding the B-mode intensity value into a first coordinate, the elasticity or velocity parameter into a second coordinate and a fixed value into a third coordinate of the color three space coordinates.

An ultrasound system for shear wave elasticity imaging (SWEI) comprising:

• an ultrasound probe;
• an ultrasound transmit wave generator and an ultrasound transmit beamformer to provide transmit signals to the ultrasound probe;
• an ultrasound receive-beamformer;
• ultrasound receive signals processing unit for generating ultrasound image data from received echo signals;
• a shear wave excitation pulse generator and a shear wave beamformer;
• an image display;
• a memory storing program instructions;
• and
• at least one processor that executes the program instructions to:
• a) acquire B-mode ultrasound images of a target region in a body under examination;
• b) select a region of interest inside the said B-mode image;
• c) transmit a shear wave excitation pulse focalized on an excitation region;
• d) measure displacements of a certain number of tracking focal points at different depths positions along each one of a predefined number of laterally staggered tracking lines within the selected region of interest;
• e) determine elasticity parameters of the regions between at least two of the tracking focal points at the same depth and on at least two adjacent tracking lines as a function of the displacements caused by the shear wave at the said tracking focal points;
• f) determine the statistical reliability of the velocity or of the elasticity parameter as calculated;
• g) modify the appearance of at least one pixel of the B-mode image inside the said regions relatively to the grey-scale B-mode image as a function of the elasticity parameter and the statistical reliability of the elasticity parameter;
• i) display the at least one pixel having the modified appearance at the corresponding pixel of the B-mode image.