Imagerie de contraste ultrasonore avec transducteurs capacitifs micro-usinés. (Contrast agent imaging with capacitive micro-machined transducers)
نویسنده
چکیده
Ultrasound Contrast Agents (UCAs) composed ofgaseous microbubbles exhibit acoustic properties that differ fromthose surrounding tissue. In order to increase the contrast totissue ratio, it is necessary to propose methods that characterizeoptimally the ultrasonic properties of UCAs. The aim of thisstudy is to measure the viscoelastic properties of UCAs using adynamic acousto-elastic method. The approach, based on theinteraction of two waves, provides non-contact and localizedmeasurements of viscoelastic and dissipative nonlinearities ofUCAs. Sonovue and BR14 UCAs (BraccoResearch, GE) were socharacterized at two different probing frequencies (1 MHZ, 2MHz) and two dilutions (1/100 and 1/1000). As expected veryhigh viscoelastic and dissipative nonlinearities were obtained.Hysteresis and asymmetries in compression and expansion areobserved for both viscoelastic and dissipative parameters. Sametrends were found for BR14 and SonoVue. The probing pulsefrequencies and the dilutions are providing different results forviscoelastic nonlinearities, whereas only dilution may have animpact on dissipative nonlinearities.
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