Shearwave dispersion ultrasound vibrometry (SDUV) for measuring tissue elasticity and viscosity

Abstract

Characterization of tissue elasticity (stiffness) and viscosity has important medical applications because these properties are closely related to pathological changes. Quantitative measurement is more suitable than qualitative measurement (i.e., mapping with a relative scale) of tissue viscoelasticity for diagnosis of diffuse diseases where abnormality is not confined to a local region and there is no normal background tissue to provide contrast. Shearwave dispersion ultrasound vibrometry (SDUV) uses shear wave propagation speed measured in tissue at multiple frequencies (typically in the range of hundreds of Hertz) to solve quantitatively for both tissue elasticity and viscosity. A shear wave is stimulated within the tissue by an ultrasound push beam and monitored by a separate ultrasound detect beam. The phase difference of the shear wave between 2 locations along its propagation path is used to calculate shear wave speed within the tissue. In vitro SDUV measurements along and across bovine striated muscle fibers show results of tissue elasticity and viscosity close to literature values. An intermittent pulse sequence is developed to allow one array transducer for both push and detect function. Feasibility of this pulse sequence is demonstrated by in vivo SDUV measurements in swine liver using a dual transducer prototype simulating the operation of a single array transducer.

Measurement of in vivo tendon function

“…This technique has been validated for assessing the mechanical properties of muscle and breast tissue, 12,30,32,80,95 and there are preliminary reports of the application of this technique in the Achilles tendons of rabbits 48 and humans. [16][17][18]43 The accuracy and reliability of this technique for quantifying in vivo tendon function has not been rigorously evaluated., however, and the long-term clinical utility of this technique is largely unknown.…”

Novel estimation method for shear wave displacement amplitude excited by vibrator

“…[1][2][3] This imaging technique has been applied to the viscosity measurement of tissues. 4,5) The accuracy of SWI was discussed by numerical simulation 6,7) and the improvement in measurement accuracy in SWI was studied. [8][9][10] Review papers have been published for SWI.…”

Método ultrassônico de detecção de microvibração: Desenvolvimento da técnica

“…Com isto, a propagação das ondas de cisalhamento torna mais viável a caracterização de meios biológicos através de parâmetros viscoelásticos (Sarvazyan et al, 1998). Uma técnica bastante utilizada para examinar alterações nas propriedades mecânicas de um meio, como por exemplo, o coeficiente de elasticidade de cisalhamento do tecido mole, é a elastografia, a qual pode estar baseada na propagação de ondas de cisalhamento no meio (Benech, 2004;Bercoff et al, 2003;Chen et al, 2009;Deffieux et al, 2009;Gennisson et al, 2004;Gennisson e Cloutier, 2006;Giannoula e Cobbold, 2007;Nightingale et al, 2001;Rengaraju et al, 2009;Sarvazyan et al, 1998;Urban et al, 2009).…”

“…Alguns pesquisadores propuseram configurações experimentais relacionadas à elastografia, nas quais foram empregadas uma fonte de vibração mecânica externa com baixa frequência, para induzir a propagação da onda transversal no meio, e um sistema de ultrassom pulso-eco (Benech, 2004;Catheline et al, 1999a;1999b;Gennisson et al, 2004;Gennisson e Cloutier, 2006) ou o Doppler ultrassônico (Gao et al, 1993;1995;Yamakoshi et al, 1990), para detectar a vibração do meio imposta pela propagação da onda de cisalhamento, a qual induz, tipicamente, vibrações da ordem de 20 mm em meios biológicos (Bercoff et al, 2004;Chen et al, 2009;Zheng et al, 2007).…”