Peggy Palanchon

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Detection and characterization of emboli in the blood stream is of high clinical importance for making decisions after surgery. In this study, a new technique based on the nonlinear oscillations of gas bubbles was applied to gaseous emboli detection, characterization and sizing. To simulate gaseous emboli, an experimental system was developed to produce air(More)
The classification of circulating microemboli as gaseous or particulate matter is essential to establish the relevance of the detected embolic signals. Until now, Doppler techniques have failed to determine unambiguously the nature of circulating microemboli. Recently, a new approach based on the analysis of radio frequency (RF) signal and using the(More)
Previous studies dealing with contrast agent microbubbles have demonstrated that ultrasound (US) can significantly influence the movement of microbubbles. In this paper, we investigated the influence of the acoustic radiation force on individual air bubbles using high-speed photography. We emphasize the effects of the US parameters (pulse length, acoustic(More)
An air bubble driven by ultrasound can become shape-unstable through a parametric instability. We report time-resolved optical observations of shape oscillations (mode n=2 to 6) of micron-sized single air bubbles. The observed mode number n was found to be linearly related to the ambient radius of the bubble. Above the critical driving pressure threshold(More)
We have presented, in a previous study, a new approach to detect, characterize and estimate the size of gaseous emboli, based on the nonlinear behavior of gaseous bubbles. In this study, a specific transducer design has been developed to be used for such a purpose. It is composed of two separate transmitting and receiving capabilities. The transmit part,(More)
Emboli detection and characterization is of importance for different patients, such as those undergoing carotid or cardiac surgery. The emboli occur as particulate or gaseous matters. To select the appropriate treatment and reduce the risk of embolism, it is essential to first detect and then classify and, ultimately, size the emboli. We propose, in this(More)
Gaseous microemboli can arise in extracorporeal lines and devices such as dialysis machines. They are associated with severe pulmonary side effects in patients undergoing chronic hemodialysis sessions. The goal of this study was to develop a gaseous emboli trapper using ultrasound waves to remove any air bubble from the tubing system before they reach the(More)
Future applications of ultrasound and microbubbles extend to more than imaging applications. Over the last few years, it was reported that sonographic contrast agent effects under ultrasound, modulate transiently cell membrane permeability. This process, named sonoporation and classified as a new physical method to transfer genes or drugs, consists of using(More)
It is now generally believed that the majority of strokes are caused by emboli from distal sites, rather than by local haemorrhagic or occlusive processes. The discovery that emboli of various types can be detected using Doppler ultrasound as they are carried through the major cerebral arteries has led to a new field of study, which appears to have(More)
In the past decade, microbubble contrast agents have evolved from a technical curiosity into a new clinical modality for ultrasound imaging. Among other achievements, microbubbles can be credited with the first real time images of myocardial perfusion that have been made by medical imaging. The agents themselves are now into their second generation,(More)