The Acoustic Scatter from Single biSphere Microbubbles

Thomas, David Hurst; Butler, Mairéad; Dermitzakis, Aris; Anderson, Thomas; McDicken, W.N.; Sboros, Vassilis

doi:10.1016/j.ultrasmedbio.2010.07.002

Cited by 5 publications

(13 citation statements)

References 28 publications

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“…The short duration echo is due to cracking of the microbubble shell prior to gas release and these results confirm previous findings on the biSphere TM acoustic response [14]. The majority of echoes of short duration on the first insonation gave a full length echo (equal to the incident pulse length) on the second insonation.…”

Section: B Lifetime Of Microbubble Echo and Duration Of Responsesupporting

confidence: 89%

“…For the free microbubbles these values were 94% and 90% respectively. As shown previously [14,16], the short duration echo is associated with a free gas oscillation outside the microbubble shell following a crack that was induced by the pressure exerted by the gas trapped inside the bubble. Following this event the generated crack provides a permanent escape route for the gas and therefore the second echo displays mostly a full duration as above.…”

Section: B Lifetime Of Microbubble Echo and Duration Of Responsesupporting

confidence: 63%

“…The rest of the microbubble population provides scatter with duration similar to that of the transmitted ultrasound. This is due to their porous shells and release their gas without the requirement to create a shell crack [14]. There are also a number of other smaller sized biSphere™ microbubbles that do not respond to ultrasound [16].…”

Section: Discussionmentioning

confidence: 99%

“…At lower acoustic pressures echoes are only detected from leaking microbubbles as the acoustic field is not enough to crack the shell [14]. The number of microbubbles that crack increases with increasing acoustic pressure.…”

Section: Discussionmentioning

confidence: 99%

“…The nature of the response of biSphere ™ is that the rigid shell, on insonation, releases the gas through shell defects or by means of ultrasound induced cracking [14], resulting in the detection of a free gas microbubble in the vicinity of a rigid shell.…”

Section: A Ultrasound Set Upmentioning

confidence: 99%

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A setup for the assessment of the effect of tubular confinement on the acoustic response of microbubbles

Butler

Dermitzakis

Looney

et al. 2014

2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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Ultrasound contrast agents are gas filled microbubbles which produced enhanced echoes in ultrasound imaging thus allowing the acquisition of detailed information on the path of blood. It is theoretically known that the size of a vessel affects the behavior of a microbubble, which could potentially be used to discriminate different sized vessels. This information would be useful in the monitoring of neovascularization in tumor growth or treatment. However, currently it is not possible to identify the vessel diameter by any means of signal processing of microbubble echoes. In order to assess microbubble behavior when confined in tubes we compared the acoustic backscatter from biSphere™ microbubbles both free in water and flowing in 200 μm diameter tubes that are similar in size to arterioles. Experimental systems that allow the interrogation of individual microbubbles were designed and modified to allow investigation of both free microbubbles and those in tubes. Unprocessed single microbubble RF data were collected, allowing the calculation of both the fundamental and second harmonic components of the backscattered signal. Microbubbles confined in tubes had lower amplitude response compared to unconfined microbubbles. On consecutive insonations of the same microbubble, free microbubbles produced echoes above noise more often than confined microbubbles. This setup may be used to investigate microbubble behavior in a range of smaller tubes with diameters similar to capillaries thus enabling signal processing design for vessel differentiation.

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Section: B Lifetime Of Microbubble Echo and Duration Of Responsesupporting

confidence: 89%

Section: B Lifetime Of Microbubble Echo and Duration Of Responsesupporting

confidence: 63%