Repeatable vaporization of optically vaporizable perfluorocarbon droplets for photoacoustic contrast enhanced imaging

Asami, Rei; Kawabata, Ken‐ichi

doi:10.1109/ultsym.2012.0299

Cited by 20 publications

(31 citation statements)

References 8 publications

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“…The success of this approach likely depends on the intended use of the droplets. For applications where droplets are used to achieve a secondary goal (such as drug delivery or enhancing ablation), or when bubbles produced by vaporization are expected to recondense shortly after the pulse ends (i.e., the droplets are below the equilibrium saturation curve at ambient conditions) [75], this is likely correct. However, when the intent is to create stable bubbles for continuing ultrasound interaction (e.g., imaging) that survive after the pulse ends, repetitive and/or long pulses can change the expected bubble distribution adversely.…”

Section: Characterization Of Submicrometer Phase-shift Dropletsmentioning

confidence: 99%

Methods of Generating Submicrometer Phase-Shift Perfluorocarbon Droplets for Applications in Medical Ultrasonography

Sheeran

Matsuura

Borden

et al. 2017

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

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Continued advances in the field of ultrasound and ultrasound contrast agents have created new approaches to imaging and medical intervention. Phase-shift perfluorocarbon droplets, which can be vaporized by ultrasound energy to transition from the liquid to the vapor state, are one of the most highly researched alternatives to clinical ultrasound contrast agents (i.e., microbubbles). In this paper, part of a special issue on methods in biomedical ultrasonics, we survey current techniques to prepare ultrasound-activated nanoscale phase-shift perfluorocarbon droplets, including sonication, extrusion, homogenization, microfluidics, and microbubble condensation. We provide example protocols and discuss advantages and limitations of each approach. Finally, we discuss best practice in characterization of this class of contrast agents with respect to size distribution and ultrasound activation.

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Section: Characterization Of Submicrometer Phase-shift Dropletsmentioning

confidence: 99%

Methods of Generating Submicrometer Phase-Shift Perfluorocarbon Droplets for Applications in Medical Ultrasonography

Sheeran

Matsuura

Borden

et al. 2017

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

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“…More recently, our group and others have developed laser‐activated nanodroplets (LANDs) containing liquid perfluorohexane and optical dye. LANDs repeatedly vaporize and recondense because the boiling point of perfluorohexane (56°C) is higher than physiological temperature (37°C) . This unique, repeatable phase‐changing property of LANDs has enabled or improved many applications, including super‐resolution imaging, background‐free imaging, and photoacoustic imaging .…”

Section: Introductionmentioning

confidence: 99%

Contrast-enhanced ultrasound imaging in vivo with laser-activated nanodroplets

et al. 2017

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Purpose This study introduces a real-time contrast-enhanced ultrasound imaging method with recently developed laser-activated nanodroplets (LANDs), a new class of phase-change nanometer-scale contrast agents that provides perceptible, sustained high-contrast with ultrasound. Methods In response to pulsed laser irradiation, the LANDs—, which contain liquid perfluorohexane and optical fuses—blink (vaporize and recondense). That is, they change their state from liquid nanodroplets to gas microbubbles, and then back to liquid nanodroplets. In their gaseous microbubble state, the LANDs provide high-contrast ultrasound, but the microbubbles formed in situ typically recondense in tens of milliseconds. As a result, LAND visualization by standard, real-time ultrasound is limited. However, the periodic optical triggering of LANDs allows us to observe corresponding transient, periodic changes in ultrasound contrast. This study formulates a probability function that measures how ultrasound temporal signals vary in periodicity. Then, the estimated probability is mapped onto a B-scan image to construct a LAND-localized, contrast-enhanced image. We verified our method through phantom and in vivo experiments using an ultrasound system (Vevo 2100, FUJIFILM VisualSonics, Inc., Toronto, ON, Canada) operating with a 40-MHz linear array and interfaced with a 10 Hz Nd:YAG laser (Phocus, Opotek Inc., Carlsbad, CA, USA) operating at the fundamental 1064 nm wavelength. Results From the phantom study, the results showed improvements in the contrast-to-noise ratio of our approach over conventional ultrasound ranging from 129% to 267%, with corresponding execution times of 0.10 s to 0.29 s, meaning that the developed method is computationally efficient while yielding high-contrast ultrasound. Furthermore, in vivo sentinel lymph node (SLN) imaging results demonstrated that our technique could accurately identify the SLN. Conclusions The results indicate that our approach enables efficient and robust LAND localization in real time with substantially improved contrast, which is essential for the successful translation of this contrast agent platform to clinical settings.

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“…Rapoport et al demonstrated repeated ultrasonic activation of a highly stable particle 20. Asami et al incorporated a dye into a high boiling point PFC droplet and vaporized it repeatedly for prolonged photoacoustic contrast 23. Arnal et al report the synthesis of a gold particle shelled PFC emulsion and a high contrast, real-time ultrasound/photoacoustic imaging technique using synchronized laser pulses 24,25.…”

Section: Introductionmentioning

confidence: 99%

Blinking Phase-Change Nanocapsules Enable Background-Free Ultrasound Imaging

Hannah¹,

Luke²,

Emelianov³

2016

Theranostics

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Microbubbles are widely used as contrast agents to improve the diagnostic capability of conventional, highly speckled, low-contrast ultrasound imaging. However, while microbubbles can be used for molecular imaging, these agents are limited to the vascular space due to their large size (> 1 μm). Smaller microbubbles are desired but their ultrasound visualization is limited due to lower echogenicity or higher resonant frequencies. Here we present nanometer scale, phase changing, blinking nanocapsules (BLInCs), which can be repeatedly optically triggered to provide transient contrast and enable background-free ultrasound imaging. In response to irradiation by near-infrared laser pulses, the BLInCs undergo cycles of rapid vaporization followed by recondensation into their native liquid state at body temperature. High frame rate ultrasound imaging measures the dynamic echogenicity changes associated with these controllable, periodic phase transitions. Using a newly developed image processing algorithm, the blinking particles are distinguished from tissue, providing a background-free image of the BLInCs while the underlying B-mode ultrasound image is used as an anatomical reference of the tissue. We demonstrate the function of BLInCs and the associated imaging technique in a tissue-mimicking phantom and in vivo for the identification of the sentinel lymph node. Our studies indicate that BLInCs may become a powerful tool to identify biological targets using a conventional ultrasound imaging system.

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Repeatable vaporization of optically vaporizable perfluorocarbon droplets for photoacoustic contrast enhanced imaging

Cited by 20 publications

References 8 publications

Methods of Generating Submicrometer Phase-Shift Perfluorocarbon Droplets for Applications in Medical Ultrasonography

Methods of Generating Submicrometer Phase-Shift Perfluorocarbon Droplets for Applications in Medical Ultrasonography

Contrast-enhanced ultrasound imaging in vivo with laser-activated nanodroplets

Blinking Phase-Change Nanocapsules Enable Background-Free Ultrasound Imaging

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