Optical and acoustical dynamics of microbubble contrast agents inside neutrophils

Paul A. Dayton, James E. Chomas, Aaron F H Lum, John S. Allen, Jonathan Lindner, Scott I. Simon, Kathy W. Ferrara

Research output: Contribution to journalArticle

112 Citations (Scopus)

Abstract

Acoustically active microbubbles are used for contrast-enhanced ultrasound assessment of organ perfusion. In regions of inflammation, contrast agents are captured and phagocytosed by activated neutrophils adherent to the venular wall. Using direct optical observation with a high-speed camera and acoustical interrogation of individual bubbles and cells, we assessed the physical and acoustical responses of both phagocytosed and free microbubbles. Optical analysis of bubble radial oscillations during insonation demonstrated that phagocytosed microbubbles experience viscous damping within the cytoplasm and yet remain acoustically active and capable of large volumetric oscillations during an acoustic pulse. Fitting a modified version of the Rayleigh-Plesset equation that describes mechanical properties of thin shells to optical radius-time data of oscillating bubbles provided estimates of the apparent viscosity of the intracellular medium. Phagocytosed microbubbles experienced a viscous damping approximately sevenfold greater than free microbubbles. Acoustical comparison between free and phagocytosed microbubbles indicated that phagocytosed microbubbles produce an echo with a higher mean frequency than free microbubbles in response to a rarefaction-first single-cycle pulse. Moreover, this frequency increase is predicted using the modified Rayleigh-Plesset equation. We conclude that contrast-enhanced ultrasound can detect distinct acoustic signals from microbubbles inside of neutrophils and may provide a unique tool to identify activated neutrophils at sites of inflammation.

Original languageEnglish (US)
Pages (from-to)1547-1556
Number of pages10
JournalBiophysical Journal
Volume80
Issue number3
StatePublished - 2001
Externally publishedYes

Fingerprint

Microbubbles
Contrast Media
Neutrophils
Phagocytosis
Acoustics
Inflammation
Viscosity
Cytoplasm
Perfusion
Observation

ASJC Scopus subject areas

  • Biophysics

Cite this

Dayton, P. A., Chomas, J. E., Lum, A. F. H., Allen, J. S., Lindner, J., Simon, S. I., & Ferrara, K. W. (2001). Optical and acoustical dynamics of microbubble contrast agents inside neutrophils. Biophysical Journal, 80(3), 1547-1556.

Optical and acoustical dynamics of microbubble contrast agents inside neutrophils. / Dayton, Paul A.; Chomas, James E.; Lum, Aaron F H; Allen, John S.; Lindner, Jonathan; Simon, Scott I.; Ferrara, Kathy W.

In: Biophysical Journal, Vol. 80, No. 3, 2001, p. 1547-1556.

Research output: Contribution to journalArticle

Dayton, PA, Chomas, JE, Lum, AFH, Allen, JS, Lindner, J, Simon, SI & Ferrara, KW 2001, 'Optical and acoustical dynamics of microbubble contrast agents inside neutrophils', Biophysical Journal, vol. 80, no. 3, pp. 1547-1556.
Dayton PA, Chomas JE, Lum AFH, Allen JS, Lindner J, Simon SI et al. Optical and acoustical dynamics of microbubble contrast agents inside neutrophils. Biophysical Journal. 2001;80(3):1547-1556.
Dayton, Paul A. ; Chomas, James E. ; Lum, Aaron F H ; Allen, John S. ; Lindner, Jonathan ; Simon, Scott I. ; Ferrara, Kathy W. / Optical and acoustical dynamics of microbubble contrast agents inside neutrophils. In: Biophysical Journal. 2001 ; Vol. 80, No. 3. pp. 1547-1556.
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