Ultrasound motion-estimation includes issuing multiple ultrasound pulses, spaced apart from each other in a propagation direction of a shear wave, to track axial motion caused by the wave. The wave has been induced by an axially-directed push. Based on the motion, autocorrelation is used to estimate an axial displacement. The estimate is used as a starting point (234) in a time-domain based motion tracking algorithm for modifying the estimate so as to yield a modified displacement. The modification can constitute an improvement upon the estimate. The issuing may correspondingly occur from a number of acoustic windows, multiple ultrasound imaging probes imaging respectively via the windows. The autocorrelation, and algorithm, operate specifically on the imaging acquired via the pulses used in tracking the motion caused by the wave that was induced by the push, the push being a single push. The algorithm may involve cross-correlation over a search area incrementally increased subject to an image matching criterion (S358).

Shear wave elastography and/or other ultrasound imaging procedures are performed using a data acquisition technique in which data are acquired with high SNR while maintaining a high PRF.sub.e, using conventional clinical ultrasound scanners. In general, ultrasound data are acquired using plane waves at different angles, after which a time alignment process is applied to the acquired data. The time alignment uses interpolation to obtain data points at higher frame rates, and the time-aligned data is compounded to increase the SNR.

For shear wave imaging with ultrasound, a direction of the ARFI beam is selected based on tissue information, such as being perpendicular to an orientation of tissue or other than perpendicular to a face of the transducer array. As a result, the estimated shear wave velocity measured perpendicular to the ARFI beam may be closer to actual shear wave velocity. Alternatively or additionally, one or more vectors of propagation of the shear wave are determined and displayed to the user, allowing the user to visualize an extent of anisotropy of the tissue to judge impact on the shear wave velocity estimation.

The invention presents methods and instrumentation for measurement or imaging of a region of an object with waves of a general nature, for example electromagnetic (EM) and elastic (EL) waves, where the material parameters for wave propagation and scattering in the object depend on the wave field strength. The invention specially addresses suppression of 3.sup.rd order multiple scattering noise, referred to as pulse reverberation noise, and also suppression of linear scattering components to enhanced signal components from nonlinear scattering. The pulse reverberation noise is divided into three classes where the invention specially addresses Class I and Class II 3.sup.rd order multiple scattering that are generated from the same three scatterers, but in opposite sequence.

Methods of triggering an imaging acquisition of a target region in an ultrasound transducer include: acquiring a first type of ultrasound data with the ultrasound transducer using a first type of ultrasound acquisition; analyzing the first type of ultrasound data to identify an acquisition time and/or position having characteristics that increase an estimated amount of image quality metrics in the target region for a second type of ultrasound acquisition; and generating a signal to initiate acquiring a second type of ultrasound data by the ultrasound transducer at the identified acquisition time and/or position using a second type of ultrasound acquisition in response to the identified acquisition time and/or position identified from the first type of ultrasound data.

To provide an ultrasonic diagnostic apparatus and an ultrasonic diagnostic method capable of conducting ultrasonic diagnosis using acoustic radiation pressure, without causing an increase in the temperature of an ultrasound-exposed portion. A push pulse transmitter outputs a coded pressurization pulse signal. A track pulse transmitter outputs a measurement pulse signal for measurement. An ultrasound probe outputs an ultrasonic wave for generating a shear wave in a target object on the basis of the pressurization pulse signal, and an ultrasonic wave for measurement on the basis of the measurement pulse signal. An echo receiver receives an echo of the ultrasonic wave for measurement, and outputs an electric signal. An elastic modulus estimator decodes the electric signal output by the echo receiver, and estimates an elastic modulus of the target object on the basis of the decoded signal.

An ultrasound processing device including an interleaver that obtains a combined wavefront frame sequence by interleaving a plurality of wavefront frame sequences; and a calculator that calculates shear wave speed and elastic modulus in a subject, by performing calculations using change amounts of propagation positions of a shear wave indicated by the combined wavefront frame sequence. The interleaving by the interleaver comprises frame interleaving and/or element array direction interleaving.

Shear waves are generated and measured in viscoelastic phantoms by a single push beam. Using numerical simulations or an analytical function to describe the diffraction of the shear wave, the resulting shear wave motion induced by the applied push beam is calculated with different shear elasticity values and then convolved with a separate expression that describes the effects of viscosity value for the medium. The optimization algorithm chooses the tissue parameters which provide the smallest difference between the measured shear waveform and the simulated shear waveform. A shear viscosity image is generated by applying such optimization procedure at all of the observation points.

A transducer array includes at least one annular shear wave generation transducer that defines an interior area, the at least one annular shear wave generation transducer being configured to generate a shear wave excitation to a region of interest such that the shear wave excitation excites at least a part of a corresponding cylindrical portion of the region of interest and shear waves propagating from the cylindrical portion of the region of interest constructively interfere in an interior region of the cylindrical portion of the region of interest; and at least one tracking transducer positioned in the interior area of the at least one annular shear wave generation transducer, the at least one tracking transducer being configured to detect a shear wave in the interior region of the region of interest.

Shear wave characteristics are estimated from analytic data. Measures of displacement are converted into complex representations. The magnitude and/or phase components of the complex representation may be used for estimating various characteristics, such as velocity, center frequency, attenuation, shear modulus, or shear viscosity. The zero-phase of the phase component represents an occurrence of the shear wave at that location.