Abstract: In shear wave imaging with an ultrasound scanner, multiple frames of shear wave data representing the same region of interest are acquired in response to a respective multiple ARFI transmissions. Instead of a fixed or same combination of focal locations for the ARFI transmissions, the focal locations of the ARFI transmissions are varied (e.g., randomly selected) between different frames of shear wave information. By combining the frames, a shear wave image may be generated with less missing data and/or shadowing effects.

Abstract: To increase the signal-to-noise ratio for displacements used to estimate the shear speed in patient tissue, constructive interference from multiple shear waves is used. By transmitting acoustic radiation force impulses focused at different locations, the resulting shear waves may constructively interfere within a region of interest. This constructive interference causes a greater amplitude of displacement. The location of this more easily detected greater interference and the difference in time of the transmitted acoustic radiation force impulses are used to estimate the shear wave speed for the tissue.

Abstract: Tissue density is quantified using shear wave information in medical ultrasound scanning. Measurements of the tissue reaction to shear waves indicate tissue density. For example, shear wave velocity is linked with density using clinical study information. The shear wave velocity in a region, over the entire tissue, or at various locations is used to determine a corresponding density or densities. The tissue density information is used for categorization, estimation of disease risk, imaging, diagnosis, or other uses. The tissue may be breast tissue or other tissue.

Abstract: Sparse tracking is used in acoustic radiation force impulse imaging. The tracking is performed sparsely. The displacements are measured only one or a few times for each receive line. While this may result in insufficient information to determine the displacement phase shift and/or maximum displacement over time, the resulting displacement samples for different receive lines as a function of time may be used together to estimate the velocity, such as with a Radon transform. The estimation may be less susceptible to noise from the scarcity of displacement samples by using compressive sensing.

Abstract: Sparse tracking is used in acoustic radiation force impulse imaging. The tracking is performed sparsely. The displacements are measured only one or a few times for each receive line. While this may result in insufficient information to determine the displacement phase shift and/or maximum displacement over time, the resulting displacement samples for different receive lines as a function of time may be used together to estimate the velocity, such as with a Radon transform. The estimation may be less susceptible to noise from the scarcity of displacement samples by using compressive sensing.

Abstract: For estimating attenuation in ultrasound imaging, displacements at different locations along an acoustic radiation force impulse (ARFI) beam are used measured. The on-axis displacements and displacements from a phantom using a same ARFI focus as a reference are used to cancel out focusing effects. A single ARFI beam may be used to estimate the attenuation for a location.

Abstract: A method and system for automatic non-invasive estimation of shear modulus and viscosity of biological tissue from shear-wave imaging is disclosed. Shear-wave images are acquired to evaluate the mechanical properties of an organ of a patient. Shear-wave propagation in the tissue in the shear-wave images is simulated based on shear modulus and viscosity values for the tissue using a computational model of shear-wave propagation. The simulated shear-wave propagation is compared to observed shear-wave propagation in the shear-wave images of the tissue using a cost function. Patient-specific shear modulus and viscosity values for the tissue are estimated to optimize the cost function comparing the simulated shear-wave propagation to the observed shear-wave propagation.

Abstract: A difference between a detected motion and a reference motion is automatically displayed. The reference motion is a modeled motion of an organ, a base line motion of an organ or another portion of an organ. A deviation in motion amplitude, angle or both angle and amplitude from a reference set may more easily identify abnormal or normal motion of the organ.

Abstract: For noise reduction in elasticity imaging, frequency compounding is used. Displacements caused by the acoustic radiation force impulse are measured using signals at different frequencies, either due to transmission of tracking pulses and reception at different frequencies or due to processing received signals at different sub-bands. The displacements are (a) combined to compound and the compounded displacements are used to determine elasticity or (b) are used to determine elasticity and the elasticities from information at the different frequencies are compounded.

Abstract: In viscoelastic imaging with ultrasound, the shear wave speed or other viscoelastic parameter is measured by tracking at the ARFI focal or other high-intensity location relative to the ARFI transmission. Rather than tracking the shear wave, the tissue response to ARFI is measured. A profile of displacements over time or a spectrum thereof is measured at the location. By finding a scale of the profile resulting in sufficient correlation with a calibration profile, the shear wave speed or other viscoelastic parameter may be estimated.

Abstract: Shear wave propagation is used to estimate the speed of sound in a patient. An ultrasound scanner detects a time of occurrence of a shear wave at each of multiple locations. The difference in time of occurrence, given tissue stiffness or shear velocity, is used to estimate the speed of sound for the specific tissue of the patient.

Abstract: Motion independent acoustic radiation force impulse imaging is provided. Rather than rely on the displacement over time for each location, the displacements over locations for each time are used. Parallel beamforming is used to simultaneously sample across a region of interest. Since it may be assumed that the different locations are subjected to the same motion at the same time, finding a peak displacement over locations for each given time provides peak or profile information independent of the motion. The velocity or other viscoelastic parameter may be estimated from the displacements over locations.

Abstract: For acoustic radiation force ultrasound imaging, multiple displacement profiles for a given location are acquired. Physiological and/or transducer axial and/or lateral motion are accounted for using the displacements from the different acoustic radiation force impulses. For axial motion, a difference between the displacements of the different profiles provides information about motion during displacement at the location caused by just the undesired motion. A more accurate estimate of the undesired motion for removing from the displacement profile is provided. For lateral motion, the displacement profiles are obtained using waves traveling from different directions relative to the given location. An average of velocities estimated from the different profiles removes undesired lateral motion.

Abstract: Detection of tissue response is provided with a high pulse repetition frequency. A sequence of separable signals is transmitted in one event. For example, pulses at different frequencies are transmitted as separate waveforms, but in rapid succession. As another example, coded transmit pulses are used. After transmission of the pulses, signals are received. Based on the different frequencies or coding, tissue response is measured at different times based on the receive event. Instead of one measure, a plurality of measures are provided for a given transmit and receive event pair, increasing the effective pulse repetition frequency for shear or elasticity imaging.

Abstract: A method and system for automatic non-invasive estimation of shear modulus and viscosity of biological tissue from shear-wave imaging is disclosed. Shear-wave images are acquired to evaluate the mechanical properties of an organ of a patient. Shear-wave propagation in the tissue in the shear-wave images is simulated based on shear modulus and viscosity values for the tissue using a computational model of shear-wave propagation. The simulated shear-wave propagation is compared to observed shear-wave propagation in the shear-wave images of the tissue using a cost function. Patient-specific shear modulus and viscosity values for the tissue are estimated to optimize the cost function comparing the simulated shear-wave propagation to the observed shear-wave propagation.

Abstract: Viscosity is included in the quantification by an ultrasound imaging system. The log of a spectrum of displacement as a function of time is determined for each of various locations subjected to a shear or other wave. Solving using the log as a function of location provides the complex wavenumber. Various viscoelastic parameters, such as loss modulus and storage modulus, are determined from the complex wavenumber.

Abstract: Information associated with shear calculation is also displayed in ultrasound shear wave imaging. More information than just a shear wave image is provided for diagnosis. Information about the quality or variables used to determine shear is also displayed. This additional information may assist the user in determining whether the shear information indicates tissue characteristics or unreliable shear calculation.

Abstract: In ARFI imaging, a cost function is used to identify a time of displacement that best or sufficiently indicates the desired information. For example, the displacements associated with a combination of contrast and signal-to-noise ratio are identified. The time at which the desired displacements occur may be other than the time of the maximum. Since the time is common to displacements for one or more scan lines, the displacement image may be assembled line-by-line or by groups of lines.

Abstract: High intensity focused ultrasound (HIFU) is registered with imaging. The effects of transmission from a HIFU transducer, such as a rise in temperature, are detected by a separate imaging system. By using multiple transmissions, a plurality of locations of the transmissions from the HIFU transducer are determined within the imaging system coordinates. A transform relating the imaging system coordinates to the HIFU transducer coordinates is determined from the detected effects. The transform may be used to relate locations indicated in images of the imaging system with coordinates of the HIFU transducer for application of HIFU. The imaging system may not have to scan the HIFU transducer or fiducials and a fixed relationship may not be needed.

Abstract: Sparse tracking is used in acoustic radiation force impulse imaging. The tracking is performed sparsely. The displacements are measured only one or a few times for each receive line. While this may result in insufficient information to determine the displacement phase shift and/or maximum displacement over time, the resulting displacement samples for different receive lines as a function of time may be used together to estimate the velocity, such as with a Radon transform. The estimation may be less susceptible to noise from the scarcity of displacement samples by using compressive sensing.