title: Transcranial sonothrombolysis using high-intensity focused ultrasound: impact of increasing output power on clot fragmentation.
abstract: BACKGROUND
  The primary goal of this study was to investigate the relationship between increasing output power levels and clot fragmentation during high-intensity focused ultrasound (HIFU)-induced thrombolysis.
  
  
  METHODS
  A HIFU headsystem, designed for brain applications in humans, was used for this project. A human calvarium was mounted inside the water-filled hemispheric transducer. Artificial thrombi were placed inside the skull and located at the natural focus point of the transducer. Clots were exposed to a range of acoustic output power levels from 0 to 400 W. The other HIFU operating parameters remained constant. To assess clot fragmentation, three filters of different mesh pore sizes were used. To assess sonothrombolysis efficacy, the clot weight loss was measured.
  
  
  RESULTS
  No evidence of increasing clot fragmentation was found with increasing acoustic intensities in the majority of the study groups of less than 400 W. Increasing clot lysis could be observed with increasing acoustic output powers.
  
  
  CONCLUSIONS
  Transcranial sonothrombolysis could be achieved in vitro within seconds in the absence of tPA and without producing relevant clot fragmentation, using acoustic output powers of <400 W.
authors.affiliation: Brain Ultrasound Research Laboratory (BURL), University of California, San Diego, 200 West Arbor Drive, San Diego, CA 92103-8756, USA ; Department of Biomedical Engineering, Wayne State University, Detroit, MI 48202, USA.
authors.forename: Golnaz
authors.initials: G
authors.lastname: Ahadi
authors.affiliation: Department of Radiology, University of California, San Diego, 200 West Arbor Drive, San Diego, CA 92103-8756, USA.
authors.forename: Christian S
authors.initials: CS
authors.lastname: Welch
authors.affiliation: Department of Biomedical Engineering, Wayne State University, Detroit, MI 48202, USA.
authors.forename: Michele J
authors.initials: MJ
authors.lastname: Grimm
authors.affiliation: Brain Ultrasound Research Laboratory (BURL), University of California, San Diego, 200 West Arbor Drive, San Diego, CA 92103-8756, USA ; Department of Radiology, University of California, San Diego, 200 West Arbor Drive, San Diego, CA 92103-8756, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Fisher
authors.affiliation: Neuro Program, InSightec, Inc., Tirat Carmel, Israel.
authors.forename: Eyal
authors.initials: E
authors.lastname: Zadicario
authors.affiliation: Department of Family and Preventive Medicine, University of California, San Diego, 200 West Arbor Drive, San Diego, CA 92103-8756, USA.
authors.forename: Karin
authors.initials: K
authors.lastname: Ernström
authors.affiliation: Brain Ultrasound Research Laboratory (BURL), University of California, San Diego, 200 West Arbor Drive, San Diego, CA 92103-8756, USA ; Department of Radiology, University of California, San Diego, 200 West Arbor Drive, San Diego, CA 92103-8756, USA.
authors.forename: Arne H
authors.initials: AH
authors.lastname: Voie
authors.affiliation: Brain Ultrasound Research Laboratory (BURL), University of California, San Diego, 200 West Arbor Drive, San Diego, CA 92103-8756, USA ; Department of Radiology, University of California, San Diego, 200 West Arbor Drive, San Diego, CA 92103-8756, USA ; Department of Neurosciences, University of California, San Diego, 200 West Arbor Drive, San Diego, CA 92103-8756, USA.
authors.forename: Thilo
authors.initials: T
authors.lastname: Hölscher
keywords: Clot debris; Clot fragmentation; High-intensity focused ultrasound; Stroke; Thrombolysis