Single Microbubble Response Using Pulse Sequences: Initial Results

Thomas, D; Butler, Mairéad; Anderson, Thomas; Steel, R.; Pye, S. D.; Poland, Marcia; Brock-Fisher, T.; McDicken, W.N.; Sboros, Vassilis

doi:10.1016/j.ultrasmedbio.2008.07.006

Cited by 19 publications

(9 citation statements)

References 41 publications

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“…In combined optical-acoustical experiments examining the response of microbubbles to low-pressure (PNP <65 kPa), 15-cycle bursts between 2 and 4 MHz, Guidi et al reported changes in damping as bubbles shrink (Guidi et al 2010). Thomas et al recently categorized the response of single shrinking bubbles to two successive pulses on the basis of spectral content at the transmitted frequency and twice the transmitted frequency (Thomas et al 2009). Underlying mechanisms of shrinkage rate and loss of core gas have recently been examined by Cox and Thomas in optical studies using three-cycle pulses at 1.1 MHz and 200 kPa peak-to-peak amplitude (Cox and Thomas 2010; Cox and Thomas 2013).…”

Section: Introductionmentioning

confidence: 99%

On the Relationship Between Microbubble Fragmentation, Deflation and Broadband Superharmonic Signal Production

Lindsey¹,

Rojas²,

Dayton³

2015

Ultrasound in Medicine & Biology

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Acoustic angiography imaging of microbubble contrast agents utilizes the superharmonic energy produced from excited microbubbles, and enables high-contrast, high-resolution imaging. However, the exact mechanism by which broadband harmonic energy is produced is not fully understood. In order to elucidate the role of microbubble shell fragmentation in superharmonic signal production, simultaneous optical and acoustic measurements were performed on individual microbubbles at transmit frequencies from 1.75 to 3.75 MHz and pressures near the shell fragmentation threshold for microbubbles of varying diameter. High-amplitude, broadband superharmonic signals were produced with shell fragmentation, while weaker signals (approximately 25% of peak amplitude) were observed in the presence of shrinking bubbles. Furthermore, when imaging populations of stationary microbubbles with a dual-frequency ultrasound imaging system, a sharper decline in image intensity with respect to frame number was observed for 1 μm bubbles than for 4 μm bubbles. Finally, in a study of two rodents, increasing frame rate from 4 to 7 Hz resulted in a decrease in mean steady-state image intensity of 27% at 1000 kPa and 29% at 1300 kPa. While the existence of superharmonic signals when bubbles shrink has the potential to prolong the imaging efficacy of microbubbles, parameters such as frame rate and peak pressure must be balanced with expected re-perfusion rate in order to maintain adequate contrast during in vivo imaging.

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Section: Introductionmentioning

confidence: 99%

On the Relationship Between Microbubble Fragmentation, Deflation and Broadband Superharmonic Signal Production

Lindsey¹,

Rojas²,

Dayton³

2015

Ultrasound in Medicine & Biology

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“…Thus, the full potential of contrast agents in improving diagnostic and therapeutic techniques has therefore not yet been achieved. By studying the response from single MBs, their interaction with ultrasound can be understood, with immediate consequences to their signal processing (Thomas et al 2008). The variations of microbubble (MB) size and shell parameters (Postema et al 2003) within a sample of contrast agent dictate that a large number of single scatterer data are necessary to obtain information on the variability of MB response, which is not possible with current optical systems.…”

Section: Introductionmentioning

confidence: 99%

The Acoustic Scatter from Single biSphere Microbubbles

Thomas

Butler

Dermitzakis

et al. 2010

Ultrasound in Medicine & Biology

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“…Systems capable of studying individual confined and unconfined contrast agent microbubbles have been previously described [8,13] Carlos, CA, USA) is a rigid shelled microbubble with an albumin coating and contains nitrogen. 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%

“…The investigation of the microbubble acoustics under different sized tube confinement is an obvious extension of these and as it will have immediate application to the signal processing. We have previously shown that studying the acoustics of single microbubbles offers useful data for the development of signal processing algorithms [8]. Single microbubble acoustics have, in addition, offered useful data that contribute to the understanding of microbubble properties [9][10][11].…”

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confidence: 99%

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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Single Microbubble Response Using Pulse Sequences: Initial Results

Cited by 19 publications

References 41 publications

On the Relationship Between Microbubble Fragmentation, Deflation and Broadband Superharmonic Signal Production

On the Relationship Between Microbubble Fragmentation, Deflation and Broadband Superharmonic Signal Production

The Acoustic Scatter from Single biSphere Microbubbles

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

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