On Lamb and Rayleigh wave convergence in viscoelastic tissues

Ivan Z. Nenadic, Matthew W Urban, Sara Aristizabal, Scott A. Mitchell, Tye C. Humphrey, James F Greenleaf

Research output: Contribution to journalArticle

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Abstract

Characterization of the viscoelastic material properties of soft tissue has become an important area of research over the last two decades. Our group has been investigating the feasibility of using a shear wave dispersion ultrasound vibrometry (SDUV) method to excite Lamb waves in organs with plate-like geometry to estimate the viscoelasticity of the medium of interest. The use of Lamb wave dispersion ultrasound vibrometry to quantify the mechanical properties of viscoelastic solids has previously been reported. Two organs, the heart wall and the spleen, can be readily modeled using plate-like geometries. The elasticity of these two organs is important because they change in pathological conditions. Diastolic dysfunction is the inability of the left ventricle (LV) of the heart to supply sufficient stroke volumes into the systemic circulation and is accompanied by the loss of compliance and stiffening of the LV myocardium. It has been shown that there is a correlation between high splenic stiffness in patients with chronic liver disease and strong correlation between spleen and liver stiffness. Here, we investigate the use of the SDUV method to quantify the viscoelasticity of the LV free-wall myocardium and spleen by exciting Rayleigh waves on the organ's surface and measuring the wave dispersion (change of wave velocity as a function of frequency) in the frequency range 40-500 Hz. An equation for Rayleigh wave dispersion due to cylindrical excitation was derived by modeling the excised myocardium and spleen with a homogenous Voigt material plate immersed in a nonviscous fluid. Boundary conditions and wave potential functions were solved for the surface wave velocity. Analytical and experimental convergence between the Lamb and Rayleigh waves is reported in a finite element model of a plate in a fluid of similar density, gelatin plate and excised porcine spleen and left-ventricular free-wall myocardium.

Original languageEnglish (US)
Pages (from-to)6723-6738
Number of pages16
JournalPhysics in Medicine and Biology
Volume56
Issue number20
DOIs
StatePublished - Oct 21 2011

Fingerprint

Spleen
Myocardium
Heart Ventricles
Elasticity
Gelatin
Stroke Volume
Compliance
Liver Diseases
Chronic Disease
Swine
Liver
Research
Ultrasonic Waves

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

Cite this

On Lamb and Rayleigh wave convergence in viscoelastic tissues. / Nenadic, Ivan Z.; Urban, Matthew W; Aristizabal, Sara; Mitchell, Scott A.; Humphrey, Tye C.; Greenleaf, James F.

In: Physics in Medicine and Biology, Vol. 56, No. 20, 21.10.2011, p. 6723-6738.

Research output: Contribution to journalArticle

Nenadic, Ivan Z. ; Urban, Matthew W ; Aristizabal, Sara ; Mitchell, Scott A. ; Humphrey, Tye C. ; Greenleaf, James F. / On Lamb and Rayleigh wave convergence in viscoelastic tissues. In: Physics in Medicine and Biology. 2011 ; Vol. 56, No. 20. pp. 6723-6738.
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