Inertial cavitation effect of catheter- based Q-switched ND:YAG laser enhance extracorporeal pulsed- focused ultrasound thrombolysis

Mehrad, H.; Farhoudi, Mehdi; Paknezhad, Alireza

doi:10.1016/j.atherosclerosis.2017.06.521

Cited by 2 publications

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…CONTRAST agents play an important role in medical ultrasound, in terms of both diagnostic imaging and therapy [1][2][3]. Microbubbles are ideal contrast agents for ultrasound imaging, and have been used for vascular imaging [4,5], drug delivery [6,7], and cavitationbased therapies [8][9][10][11] (e.g. temporal blood-brain barrier opening [12]).…”

Section: Introductionmentioning

confidence: 99%

Leveraging the Imaging Transmit Pulse to Manipulate Phase-Change Nanodroplets for Contrast-Enhanced Ultrasound

Zhu

Zhao

Emelianov

2019

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

View full text Add to dashboard Cite

Phase-change perfluorohexane nanodroplets (PFHnDs) are a new class of recondensable submicrometer-sized contrast agents that have potential for contrast-enhanced and super-resolution ultrasound imaging with an ability to reach extravascular targets. The PFHnDs can be optically triggered to undergo vaporization, resulting in spatially stationary, temporally transient microbubbles. The vaporized PFHnDs are hyperechoic in ultrasound imaging for several to hundreds of milliseconds before recondensing to their native, hypoechoic, liquid nanodroplet state. The decay of echogenicity, i.e., the dynamic behavior of the ultrasound signal from optically triggered PFHnDs in ultrasound imaging, can be captured using high frame rate ultrasound imaging. We explore the possibility to manipulate the echogenicity dynamics of optically triggered PFHnDs in ultrasound imaging by changing the phase of the ultrasound imaging pulse. Specifically, the ultrasound imaging system was programmed to transmit two imaging pulses with inverse polarities. We show that the imaging pulse phase can affect the amplitude and the temporal behavior of PFHnD echogenicity in ultrasound imaging. The results of this study demonstrate that the ultrasound echogenicity is significantly increased (about 78% improvement) and the hyperechoic timespan of optically triggered PFHnDs is significantly longer (about 4 times) if the nanodroplets are imaged by an ultrasound pulse starting with rarefactional pressure versus a pulse starting with compressional pressure. Our finding has direct and significant implications for contrast-enhanced ultrasound imaging of droplets in applications such as super-resolution imaging and molecular imaging where detection of individual or low-concentration PFHnDs is required.

show abstract

Section: Introductionmentioning

confidence: 99%

Leveraging the Imaging Transmit Pulse to Manipulate Phase-Change Nanodroplets for Contrast-Enhanced Ultrasound

Zhu

Zhao

Emelianov

2019

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

View full text Add to dashboard Cite

show abstract

Dynamic assessment of dual-frequency microbubble-mediated sonothrombolysis in vitro

Suo

Govind

et al. 2019

Journal of Applied Physics

View full text Add to dashboard Cite

Optimizing the use of high intensity focused ultrasound (HIFU) for recanalization of occluded blood vessels is an actively researched area. This yields an alternative therapy to the use of thrombolytic drugs in the treatment of ischemic stroke. HIFU treatment, used in conjunction with microbubbles (MBs) in the fluid stream, serves to augment the dissipation of the blood clot. In this study, using an in vitro approach, we implement a flow system to simulate the dynamic dispersion of blood clots using single-frequency focused ultrasound (SFFU) and dual-frequency focused ultrasound (DFFU). The effects of permutations of acoustic power and driving frequency (SFFU vs. DFFU) on the rate of disintegration and site-specific lytic action are quantified under the influence of fluid akin to that in a blood vessel, for specific microbubble concentrations. It is found that dual-frequency excitation in general produces a faster rate of clot dissipation in comparison to single-frequency excitation, and this observation is corroborated by cavitation signal detection. Our observations indicate that accelerated thrombolysis may be realized by the inertial cavitation threshold of DFFU being lower than that of SFFU. Furthermore, the thrombolytic effect with variance in microbubble concentration is studied for a fixed acoustic power. The efficacy of DFFU is not found to vary appreciably with an increase in microbubble concentration from 108 MBs/ml to 109 MBs/ml, possibly due to acoustic shadowing induced at increased concentrations.

show abstract

Inertial cavitation effect of catheter- based Q-switched ND:YAG laser enhance extracorporeal pulsed- focused ultrasound thrombolysis

Cited by 2 publications

References 0 publications

Leveraging the Imaging Transmit Pulse to Manipulate Phase-Change Nanodroplets for Contrast-Enhanced Ultrasound

Leveraging the Imaging Transmit Pulse to Manipulate Phase-Change Nanodroplets for Contrast-Enhanced Ultrasound

Dynamic assessment of dual-frequency microbubble-mediated sonothrombolysis in vitro

Contact Info

Product

Resources

About