Title :
In vivo measurements of viscoelasticity of the swine heart using Shearwave Dispersionc Ultrasound Vibrometry (SDUV)
Author :
Urban, Matthew W. ; Pislaru, Cristina ; Kinnick, Randall R. ; Greenleaf, James F.
Author_Institution :
Dept. of Physiol. & Biomed. Eng., Mayo Clinic Coll. of Med., Rochester, MN, USA
Abstract :
Quantification of the viscoelastic properties of the myocardium using ultrasound may aid with evaluation of the health of the heart. Shearwave Dispersion Ultrasound Vibrometry (SDUV) is a method that uses dispersion, or variation with frequency, of shear wave velocities to characterize the underlying viscoelastic material properties of soft tissue. We studied eight pigs in an open-chest preparation, using a mechanical actuator to create harmonic, propagating mechanical waves in the myocardial wall. The motion was tracked using a high frame rate acquisition sequence, typically 2500 Hz, with a Sonix RP system. The velocities of wave propagation were measured over the range 50-350 Hz in 50 Hz increments. Data were acquired over several cardiac cycles. Dispersion curves were fit with a viscoelastic, asymmetrical Lamb wave model to obtain estimates of the shear elasticity, μ1, and viscosity, μ2. We found excellent agreement between the elastic term measured by SDUV and the shear elastic modulus measured by pressure-segment length analysis. We demonstrated that SDUV measurements and Lamb wave theory allow us to estimate the variation of viscoelastic moduli of the myocardial walls in vivo throughout the course of the cardiac cycle.
Keywords :
biomechanics; biomedical ultrasonics; cardiology; ultrasonic measurement; ultrasonic propagation; viscometers; Shearwave Dispersion Ultrasound Vibrometry; Sonix RP system; asymmetrical Lamb wave model; dispersion curves; frequency 2500 Hz; frequency 50 Hz to 350 Hz; heart health; mechanical actuator; myocardium; open-chest preparation; pigs; shear elasticity; swine heart; viscoelasticity; viscosity; Dispersion; Heart; Imaging; In vivo; Myocardium; Ultrasonic imaging; Ultrasonic variables measurement; Lamb waves; heart; shear waves; viscoelasticity;
Conference_Titel :
Ultrasonics Symposium (IUS), 2010 IEEE
Conference_Location :
San Diego, CA
Print_ISBN :
978-1-4577-0382-9
DOI :
10.1109/ULTSYM.2010.5935764