title: Cavitation thresholds of contrast agents in an in vitro human clot model exposed to 120-kHz ultrasound.
abstract: Ultrasound contrast agents (UCAs) can be employed to nucleate cavitation to achieve desired bioeffects, such as thrombolysis, in therapeutic ultrasound applications. Effective methods of enhancing thrombolysis with ultrasound have been examined at low frequencies (<1 MHz) and low amplitudes (<0.5 MPa). The objective of this study was to determine cavitation thresholds for two UCAs exposed to 120-kHz ultrasound. A commercial ultrasound contrast agent (Definity(®)) and echogenic liposomes were investigated to determine the acoustic pressure threshold for ultraharmonic (UH) and broadband (BB) generation using an in vitro flow model perfused with human plasma. Cavitation emissions were detected using two passive receivers over a narrow frequency bandwidth (540-900 kHz) and a broad frequency bandwidth (0.54-1.74 MHz). UH and BB cavitation thresholds occurred at the same acoustic pressure (0.3 ± 0.1 MPa, peak to peak) and were found to depend on the sensitivity of the cavitation detector but not on the nucleating contrast agent or ultrasound duty cycle.
authors.affiliation: Biomedical Engineering Program, University of Cincinnati, Cardiovascular Center 3941, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0586.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Gruber
authors.affiliation: Department of Internal Medicine, Division of Cardiovascular Health and Diseases, University of Cincinnati, Cardiovascular Center 3941, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0586.
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Bader
authors.affiliation: Department of Internal Medicine, Division of Cardiovascular Health and Diseases, University of Cincinnati, Cardiovascular Center 3941, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0586.
authors.forename: Christy K
authors.initials: CK
authors.lastname: Holland
mesh_terms: D003287:Contrast Media / Q000737:chemistry*; D005466:Fluorocarbons / Q000737:chemistry*; D006801:Humans; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes; D061185:Mechanical Thrombolysis / Q000379:methods*; D011312:Pressure; D013016:Sound; D013927:Thrombosis / Q000628:therapy*; D014464:Ultrasonic Therapy / Q000379:methods*; D014732:Vibration
chemical_list: D003287:Contrast Media; D005466:Fluorocarbons; D008055:Lipids; D008081:Liposomes; C042852:perflutren