title: Effect of microbubble fragility on transit rate measurement by contrast echography.
abstract: We sought to propose a simplified method to measure flow velocity based on ultrasonic microbubble destruction, and investigated the effect of microbubble shell fragility on such measurement. Acoustic density (AD) from the second harmonic short axis image of flow was obtained at variable velocities (2 to 73 mm/s) in an in vitro model during long (1000 ms) and short (33 ms) interval ultrasound (US) pulsing, allowing complete and partial microbubble replenishment between pulses, respectively. Microbubbles with shell elastic modulus of 0.4 MPa and 16 MPa were tested. By shortening pulsing interval, AD diminished gradually, rather than abruptly, to a plateau level for both microbubbles. The extent of AD decay was greater for the fragile than the strong microbubbles. A linear relationship existed between the magnitude of AD decay and flow velocity only in the higher and lower velocity range for the fragile and the strong microbubbles, respectively. Thus, difference in contrast intensities during long and short pulsing intervals, respectively, allowing complete and partial replenishment may provide for velocity measurement, in which choice of optimal microbubble fragility for the range of velocity to measure may increase the accuracy.
authors.affiliation: Second Department of Internal Medicine, Kagawa Medical University, School of Medicine, Kita-gun, Japan. komori@kms.ac.jp
authors.forename: Koji
authors.initials: K
authors.lastname: Ohmori
authors.forename: Anthony N
authors.initials: AN
authors.lastname: DeMaria
authors.forename: Bruno
authors.initials: B
authors.lastname: Cotter
authors.forename: Oi Ling
authors.initials: OL
authors.lastname: Kwan
authors.forename: Akira
authors.initials: A
authors.lastname: Oshita
authors.forename: Isao
authors.initials: I
authors.lastname: Kondo
authors.forename: Katsufumi
authors.initials: K
authors.lastname: Mizushige
authors.forename: Masakazu
authors.initials: M
authors.lastname: Kohno
mesh_terms: D002214:Capsules; D003287:Contrast Media; D023921:Coronary Stenosis / Q000000981:diagnostic imaging*; D004452:Echocardiography; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D009584:Nitrogen; D012039:Regional Blood Flow
chemical_list: D002214:Capsules; D003287:Contrast Media; D009584:Nitrogen