title: Nondestructive subharmonic imaging.
abstract: Ultrasound contrast agent microbubbles are intravascular agents that can be used to estimate blood perfusion. Blood perfusion may be estimated by destroying the bubbles in a vascular bed and observing the refresh of contrast agents back into the vascular bed. Contrast agents can be readily destroyed by traditional imaging techniques. The design of a nondestructive imaging technique is necessary for the accurate quantification of contrast agent refresh. In this work, subharmonic imaging is investigated as a method for nondestructive imaging with the contrast agent microbubble MP1950 (Mallinckrodt, Inc., St. Louis, MO). Optical observation during insonation, in conjunction with a modified Rayleigh-Plesset (R-P) analysis, provides insight into the mechanisms of and parameters required for subharmonic frequency generation. Subharmonic imaging with a transmission frequency that is the same as the resonant frequency of the bubble is shown to require a minimum pressure of insonation that is greater than the experimentally-observed bubble destruction threshold. Subharmonic imaging with a transmission frequency that is twice the resonant frequency of the bubble produces a subharmonic frequency response while minimizing bubble instability. Optimization is performed using optical experimental analysis and R-P analysis.
authors.affiliation: University of California, Department of Biomedical Engineering, Davis 95616, USA.
authors.forename: James
authors.initials: J
authors.lastname: Chomas
authors.forename: Paul
authors.initials: P
authors.lastname: Dayton
authors.forename: Donovan
authors.initials: D
authors.lastname: May
authors.forename: Katherine
authors.initials: K
authors.lastname: Ferrara
mesh_terms: D001808:Blood Vessels / Q000000981:diagnostic imaging; D003287:Contrast Media; D008863:Microspheres; D008954:Models, Biological; D012039:Regional Blood Flow; D018084:Ultrasonography, Interventional / Q000379:methods*
chemical_list: D003287:Contrast Media