title: Interfacial Rheological Properties of Contrast Microbubble Targestar P as a Function of Ambient Pressure.
abstract: In this Technical Note, we determine the interfacial rheological parameters of the encapsulation of the contrast agent Targestar P using ultrasound attenuation. The characteristic parameters are obtained according to two interfacial rheological models. The properties-surface dilatational elasticity (0.09 ± 0.01 N/m) and surface dilatational viscosity (8 ± 0.1E-9 N·s/m)-are found to be of similar magnitude for both models. Contrast microbubbles experience different ambient pressure in different organs. We also measure these parameters as functions of ambient pressure using attenuation measured at different overpressures (0, 100 and 200 mm Hg). For each value of ambient hydrostatic pressure, we determine the rheological properties, accounting for changes in the size distribution caused by the pressure change. We discuss different models of size distribution change under overpressure: pure adiabatic compression or gas exchange with surrounding medium. The dilatational surface elasticity and viscosity are found to increase with increasing ambient pressure.
authors.affiliation: Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052, USA.
authors.forename: Krishna N
authors.initials: KN
authors.lastname: Kumar
authors.affiliation: Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052, USA. Electronic address: sarkar@gwu.edu.
authors.forename: Kausik
authors.initials: K
authors.lastname: Sarkar
mesh_terms: D002214:Capsules / Q000737:chemistry* / Q000528:radiation effects*; D003287:Contrast Media / Q000737:chemistry*; D055119:Elastic Modulus / Q000528:radiation effects; D005466:Fluorocarbons / Q000737:chemistry* / Q000528:radiation effects; D019220:High-Energy Shock Waves; D008422:Materials Testing; D010316:Particle Size; D010743:Phospholipids / Q000737:chemistry* / Q000528:radiation effects; D011312:Pressure; D011829:Radiation Dosage; D033081:Shear Strength / Q000528:radiation effects; D013499:Surface Properties / Q000528:radiation effects; D014783:Viscosity / Q000528:radiation effects
chemical_list: D002214:Capsules; D003287:Contrast Media; D005466:Fluorocarbons; D010743:Phospholipids; C108042:perfluorobutane
keywords: Attenuation; Bubble dynamics; Contrast agents; Encapsulation; Gas diffusion; Interfacial rheology; Pressure estimation; Shell