title: Effects of attenuation and thrombus age on the success of ultrasound and microbubble-mediated thrombus dissolution.
abstract: The purpose of this study was to examine the effects of applied mechanical index, incident angle, attenuation and thrombus age on the ability of 2-D vs. 3-D diagnostic ultrasound and microbubbles to dissolve thrombi. A total of 180 occlusive porcine arterial thrombi of varying age (3 or 6 h) were examined in a flow system. A tissue-mimicking phantom of varying thickness (5 to 10 cm) was placed over the thrombosed vessel and the 2-D or 3-D diagnostic transducer aligned with the thrombosed vessel using a positioning system. Diluted lipid-encapsulated microbubbles were infused during ultrasound application. Percent thrombus dissolution (%TD) was calculated by comparison of clot mass before and after treatment. Both 2-D and 3-D-guided ultrasound increased %TD compared with microbubbles alone, but %TD achieved with 6-h-old thrombi was significantly less than 3-h-old thrombi. Thrombus dissolution was achieved at 10 cm tissue-mimicking depths, even without inertial cavitation. In conclusion, diagnostic 2-D or 3-D ultrasound can dissolve thrombi with intravenous nontargeted microbubbles, even at tissue attenuation distances of up to 10 cm. This treatment modality is less effective, however, for older aged thrombi.
authors.affiliation: Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198-2265, USA. fxie@unmc.edu
authors.forename: Feng
authors.initials: F
authors.lastname: Xie
authors.forename: E Carr
authors.initials: EC
authors.lastname: Everbach
authors.forename: Shunji
authors.initials: S
authors.lastname: Gao
authors.forename: Lucas K
authors.initials: LK
authors.lastname: Drvol
authors.forename: William T
authors.initials: WT
authors.lastname: Shi
authors.forename: Francois
authors.initials: F
authors.lastname: Vignon
authors.forename: Jeff E
authors.initials: JE
authors.lastname: Powers
authors.forename: John
authors.initials: J
authors.lastname: Lof
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Porter
mesh_terms: D000818:Animals; D006801:Humans; D045423:Microbubbles / Q000627:therapeutic use; D013927:Thrombosis / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome; D014464:Ultrasonic Therapy