Siemens Medical Solutions Usa, Inc.

Seungsoo Kim

Liexiang Fan

Yassin Labyed

David P Duncan

Stephen J Rosenzweig

Nikolas Ivancevich

Stephen J Hsu

Manoj G Menon

Nikolas M Ivancevich

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.

Sound speed imaging using shear waves

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.

Frequency compounding in elasticity imaging

Shear waves are detected with ultrasound. The detection of the shear wave is constrained using prior measurements in a more controlled environment (e.g., less noise). For example, shear waves measured in a phantom are used to constrain the detection of shear waves in a patient to avoid false positive detections.

Shear wave detection in medical ultrasound imaging

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.

Sparse tracking in acoustic radiation force impulse imaging

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.

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Sammamish, WA, United States of America

Seungsoo Kim