Document Detail

Nonlinear emission from individual bound microbubbles at high frequencies.
MedLine Citation:
PMID:  20018429     Owner:  NLM     Status:  MEDLINE    
Targeted microbubbles detected with high-frequency ultrasound can establish the molecular expression of blood vessels with submillimeter resolution. To improve microbubble-specific imaging at high frequencies, the subharmonic and second harmonic signal from individual microbubbles were measured as a function of size and pressure. Single phospholipid-shell microbubbles (1.1 to 5.0 microm in diameter) bound to gelatin, co-aligned with an optical microscope and transducer, were insonated with 30 MHz Gaussian-enveloped pulses at pressures from 20 kPa to 1 MPa with -6 dB one-way bandwidths of 11%, 20% and 45%. A subharmonic signal (15 MHz) was detected above a pressure threshold of 110 kPa--independent of bandwidth. The signal peaked for microbubbles 1.60 microm in diameter subject to 20% and 11% bandwidth pulses, and 1.80 microm for 45% bandwidth pulses, for pressures up to 400 kPa, agreeing with the notion that microbubbles insonated at twice their resonant frequency preferentially emit a subharmonic component. For pressures between 400 kPa and 1 MPa, a broader range of microbubbles emitted a subharmonic signal, and microbubbles below 1.70 mum in diameter were disrupted. The second harmonic signal measured, within the limited experimental conditions, was consistent with nonlinear propagation. Further, the results shed light on the effect of the shell on the phase of the subharmonic signal with respect to the fundamental signal.
Michael R Sprague; Emmanuel Ch?rin; David E Goertz; F Stuart Foster
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-12-16
Journal Detail:
Title:  Ultrasound in medicine & biology     Volume:  36     ISSN:  1879-291X     ISO Abbreviation:  Ultrasound Med Biol     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-02-01     Completed Date:  2010-03-25     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0410553     Medline TA:  Ultrasound Med Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  313-24     Citation Subset:  IM    
Copyright Information:
2010. Published by Elsevier Inc. All rights reserved.
Department of Medical Biophysics, Sunnybrook Research Institute, University of Toronto, Ontario, Canada.
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MeSH Terms
Image Enhancement / methods*
Optical Devices
Particle Size
Grant Support
//Canadian Institutes of Health Research
Reg. No./Substance:

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