Author: Acconcia C1, Leung BY2, Manjunath A2, Goertz DE3
1Department of Medical Biophysics, University of Toronto, Toronto, Canada; Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Canada. Electronic address: email@example.com.
2Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Canada.
3Department of Medical Biophysics, University of Toronto, Toronto, Canada; Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Canada.
Conference/Journal: Ultrasound Med Biol.
Date published: 2015 Oct
Other: Volume ID: 41 , Issue ID: 10 , Pages: 2774-82 , Special Notes: doi: 10.1016/j.ultrasmedbio.2015.05.011. Epub 2015 Jun 23. , Word Count: 228
In previous work, we examined microscale interactions between microbubbles and fibrin clots under exposure to 1 ms ultrasound pulses. This provided direct evidence that microbubbles were capable of deforming clot boundaries and penetrating into clots, while also affecting fluid uptake and inducing fibrin network damage. Here, we investigate the effect of short duration (15 μs) pulses on microscale bubble-clot interactions as function of bubble diameter (3-9 μm) and pressure. Individual microbubbles (n = 45) were placed at the clot boundary with optical tweezers and exposed to 1 MHz ultrasound. High-speed (10 kfps) imaging and 2-photon microscopy were performed during and after exposure, respectively. While broadly similar phenomena were observed as in the 1 ms pulse case (i.e., bubble penetration, network damage and fluid uptake), substantial quantitative differences were present. The pressure threshold for bubble penetration was increased from 0.39 MPa to 0.6 MPa, and those bubbles that did enter clots had reduced penetration depths and were associated with less fibrin network damage and nanobead uptake. This appeared to be due in large part to increased bubble shrinkage relative to the 1 ms pulse case. Stroboscopic imaging was performed on a subset of bubbles (n = 11) and indicated that complex bubble oscillations can occur during this process.
Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
KEYWORDS: Contrast agent; Fibrin clot; Microbubbles; Sonothrombolysis; Stroke; Thrombolysis; Ultrasound
PMID: 26116160 [PubMed - indexed for MEDLINE]