Doppler ultrasound detection of shear waves remotely induced in tissue phantoms and tissue in vitro

Material properties from acoustic radiation force step response

“…Stationary harmonic forces at radial frequency applied along the y 1 axis and of the form F͑t͒ = F ,1 exp͑−it͒ generate sphere velocities of the form v s ͑t͒ = v ,1 exp͑−it͒. In that situation, the material properties that influence Z are gel density Ӎ 1 g/ cm 3 , sphere radius a = 0.75 mm, and the complex Lamè moduli Ј= 1 − i 2 and Ј = 1 − i 2 . 1 is shear elasticity, 2 is shear viscosity, 1 is volume compressibility, and 2 is volumetric viscosity.…”

“…[1][2][3][4][5][6][7] Its diagnostic value stems from the important role of the cellular mechanoenvironment in regulating tumor growth 8 and from the large tumor contrast observed for various mechanical properties. 9 Biological sources of elastic strain contrast in mammary tissues include edema, hyperplasia, acidosis, fibrosis, desmoplasia, and inflammatory responses characteristic of the reaction of breast stroma to cancer cells.…”

“…This load bandwidth is nominally 100-1000 Hz depending on experimental details. Other acoustic-based approaches, including ultrasoundstimulated vibro-acoustic spectography, 2 shear wave elasticity imaging, 3 and harmonic motion imaging, 4 probe load bandwidths somewhere between these two extremes. It is difficult to design studies to discover diseasespecific sources of elasticity contrast for any of these imaging techniques.…”

Tissue displacements during acupuncture using ultrasound elastography techniques

“…This force can then be concentrated over the focal area of the transducer, that is usually of the order of a few square millimeters. As a result, borrowing again from mechanical testing principles, the images that are generated depict only the displacement amplitude as a result of the generation of the radiation force (Barannik et al 2002;Konofagou and Hynynen 2003;Nightingale et al 2001;Walker et al 2000). In this study, we have developed a new technique combining computer-controlled acupuncture needling with ultrasonic signal-processing methods to quantify tissue displacement during acupuncture needle manipulation in vivo.…”

Elastography for breast cancer diagnosis using radiation force: System development and performance evaluation

“…Kinetic acoustic vitroretinal examination (KAVE) uses radiation force to generate steady-state stresses, and the displacements are monitored to characterize the response of the tissues (Viola et al 2003). Supersonic imaging (Bercoff et al 2004b) and shear wave elasticity imaging (SWEI) (Barannik et al 2002) characterize the shear modulus of the medium by mapping the velocity of shear waves generated by a short duration acoustic radiation force. High intensity focused ultrasound (HIFU) transducers have also been studied to monitor ablation treatment by generating radiation force in conjunction with a piston to track displacements (Lizzi et al 2003).…”