Changes in tissue stiffness have long been associated with disease. Systems and methods for determining the stiffness of tissues using ultrasonography may include a device for inducing a propagating shear wave in tissue and tracking the speed of propagation, which is directly related to tissue stiffness and density. The speed of a propagating shear wave may be detected by imaging a tissue at a high frame rate and detecting the propagating wave as a perturbance in successive image frames relative to a baseline image of the tissue in an undisturbed state. In some embodiments, sufficiently high frame rates may be achieved by using a ping-based ultrasound imaging technique in which unfocused omni-directional pings are transmitted (in an imaging plane or in a hemisphere) into a region of interest. Receiving echoes of the omnidirectional pings with multiple receive apertures allows for substantially improved lateral resolution.

A method for measuring a viscoelastic parameter of an organ, includes emitting ultrasonic shots by an ultrasonic transducer; receiving by the transducer and recording the reflected ultrasonic signals; determining a viscoelastic parameter of the organ based on the recorded ultrasonic signals. The ultrasonic shots are formed by K groups of shots, separated temporally, K being greater than or equal to 1. Each K group is formed by the repetition, with a rate of PRF2, of MK blocks of ultrasonic shots, MK being greater than or equal to 1; each MK block is composed of N ultrasonic shots, N being greater than or equal to 1, PRF1 being the rate of emission of the N shots when N is chosen greater than 1; the N ultrasonic shots are distributed over P frequencies, P being between 1 and N, at least two ultrasonic shots belonging to two different blocks having different frequencies.

Methods, systems, and computer readable media for taking measurements of a material, including determining material anisotropy, are provided. According to one aspect, a method for determining tissue anisotropy comprises: applying, to a tissue sample, a first force having a direction and having a coronal plane normal to the direction of the force, the first force having an oval or other profile with long and short axes within the coronal plane, the long axis being oriented in a first direction within the coronal plane, and measuring a first displacement of the tissue; applying, to the tissue sample, a second force, and measuring a second displacement of the tissue; and calculating a tissue elasticity anisotropy based on the measured first and second displacements. Furthermore, by applying the first and second forces multiple times, tissue viscosity, elasticity, or other anisotropy may be calculated from the multiple displacement measurements.

An ultrasonic diagnostic imaging system acquires different kinds of pilot images showing different characteristics of a region of a body where shearwave measurements are performed. The pilot images are analyzed by a push pulse locator to adaptively generate push pulses at locations in the body which minimize or avoid shearwave travel through blood vessels, through regions of stiffness inhomogeneities in the body, or at times when shearwaves are adversely affected by tissue motion.

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.

An ultrasound diagnostic device detecting shear wave propagation velocity through push pulse transmission. The ultrasound diagnostic device includes: a push pulse transmitter that transmits a push pulse; a detection wave transmitter/receiver that, following the push pulse transmission, transmits plane wave transmission detection waves towards a region of interest (ROI) inside a subject and receives reflection detection waves from the subject, to generate receive signals sequentially; a displacement detector that detects subject tissue displacement occurring inside the ROI due to a shear wave; and a shear wave analyzer that detects a shear wave propagation velocity based on the subject tissue displacement. The transmission detection waves at least include transmission detection waves transmitted by the detection wave transmitter/receiver at a first transmission interval and transmission detection waves transmitted by the detection wave transmitter/receiver at a second transmission interval longer than the first transmission interval.

Systems and methods for ultrasound imaging using a delay-encoded harmonic imaging (“DE-HI”) technique is provided. An ultrasound pulse sequence is coded using temporal delays between ultrasound emissions within a single transmission event. This coded scheme allows for harmonic imaging to be implemented. The temporal time delay-codes are applied temporally to multiple different ultrasound emissions within a single transmission event, rather than spatially across different transmitting elements. The received radio frequency (“RF”) signals undergo a decoding process in the frequency domain to recover the signals, as they would be obtained from standard single emissions, for subsequent compounding. As one specific example, a one-quarter period time delay can be used to encode second harmonic signals from each angle emission during a single multiplane wave (“MW”) transmission event, rather than inverting the polarity of the pulses as in conventional MW imaging.

A shear wave velocity is accurately measured. Time change data of a displacement of a tissue due to a shear wave generated in a test object is calculated from a reception signal obtained by transmitting an ultrasonic wave to the test object and receiving a reflected wave. The time change data of the displacement is converted into spectrum data indicating a displacement distribution in a frequency space having a spatial frequency and a time frequency as two axes. Spectrum data in a predetermined region is extracted by rotating the spectrum data by a predetermined angle in the frequency space, and filtering the rotated spectrum data. A velocity of the shear wave is calculated based on the extracted spectrum data in the predetermined region.

Described herein are Compressive Sensing algorithms developed for automated reduction of NDE/SHM data from pitch-catch ultrasonic guided waves as well as a methodology using Compressive Sensing at two stages in the data acquisition and analysis process to detect damage: (1) temporally undersampled sensor signals from (2) spatially undersampled sensor arrays, resulting in faster data acquisition and reduced data sets without any loss in damage detection ability.

Circuitry for ultrasound devices is described. A multilevel pulser is described, which can provide bipolar pulses of multiple levels. The multilevel pulser includes a pulsing circuit and pulser and feedback circuit. Symmetric switches are also described. The symmetric switches can be positioned as inputs to ultrasound receiving circuitry to block signals from the receiving circuitry.