The authors regret that there was a mistake in reporting the mol% of the microbubble coating composition used. For all experiments, the unit in mg/mL was used and the conversion mistake occurred only when converting to mol% to define the ratio between the coating formulation components. The correct molecular weight of PEG-40 stearate is 2046.54 g/mol (Shen et al. 2008; Kilic and Bolukcu 2018), not 328.53 g/mol. On page 1433, the sentence should read “The lipid coating was composed of 84.8 mol% DSPC (P6517, Sigma-Aldrich, Zwijndrecht, Netherlands) or DPPC (850355, Avanti Polar Lipids, Alabaster, AL, USA); 8.2 mol% polyoxyethylene-40-stearate (PEG40 stearate, P3440, Sigma-Aldrich); 5.9 mol% 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[carboxy(polyethylene glycol)2000 (DSPE-PEG2000, 880125, Avanti Polar Lipids); and 1.1 mol% 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[biotinyl(polyethylene glycol)-2000] (DSPE-PEG2000-biotin) (880129, Avanti Polar Lipids).” This correction does not change the conclusions published in this work. The authors apologize for any inconvenience caused.

Introduction: To improve carotid artery stenting (CAS), more information about the functioning of the stent is needed. Therefore, a method that can image the flow near and around a stent is required. The aim of this study was to evaluate the performance of high-frame-rate contrast-enhanced ultrasound (HFR CEUS) in the presence of a stent. Methodology: HFR CEUS acquisitions of a carotid artery phantom, a silicone tube with diameter 8 mm, with and without a stent were acquired at transmit voltages of 2V, 4V and 10V using a Verasonics ultrasound system and C5-2 probe. Different concentrations of ultrasound contrast agent (UCA) were tested in a blood mimicking fluid (BMF). Particle image velocimetry (PIV) analysis was performed on Singular Value Decomposition (SVD) filtered images. Mean and peak velocities, and correlation coefficients were compared between stented and non-stented regions. Also, experimental results were compared with theoretical and numerical models. Results: The averaged experimental mean velocity (0.113 m/s) was significant lower than the theoretical and numerical mean velocity (0.129 m/s). The averaged experimental peak velocity (0.152 m/s) was significant lower than the theoretical and numerical peak velocity (0.259 m/s). Correlation coefficients and averaged mean velocity values were lower (difference of 0.022 m/s) in stented regions compared to non-stented regions. Conclusion: In vitro experiments showed an underestimation of mean and peak velocities in stented regions compared to non-stented regions. However, the microbubbles can be tracked efficiently and the expected laminar flow profile can be quantified using HFR CEUS near and around a stent.

Polymeric microcapsules with a light-absorbing dye incorporated in their shell can generate vapor microbubbles that can be spatiotemporally controlled by pulsed laser irradiation. These contrast agents of 6–8 μm in diameter can circulate through the vasculature, offering possibilities for ultrasound (molecular) imaging and targeted therapies. Here, we study the impact of such vapor bubbles on human endothelial cells in terms of cell poration and cell viability to establish the imaging and therapeutic windows. Two capsule formulations were used: the first one consisted of a high boiling point oil (hexadecane), whereas the second was loaded with a low boiling point oil (perfluoropentane). Poration probability was already 40% for the smallest bubbles that were formed (<7.5 μm diameter), and reached 100% for the larger bubbles. The hexadecane-loaded capsules also produced bubbles while their shell remained intact. These encapsulated bubbles could therefore be used for noninvasive ultrasound imaging after laser activation without inducing any cell damage. The controlled and localized cell destruction achieved by activation of both capsule formulations may provide an innovative approach for specifically inducing cell death in vivo, e.g., for cancer therapy.

The sensitivity and efficiency in contrast-enhanced ultrasound imaging and therapy can potentially be increased by the use of resonant monodisperse bubbles. However, bubbles of the same size may respond differently to ultrasound due to differences in their phospholipid shell. In an acoustic bubble sorting chip, resonant bubbles can be separated from the polydisperse agent. Here, a sample of acoustically sorted bubbles is characterized by measuring scattering and attenuation simultaneously using narrowband acoustic pulses at peak negative pressures of 10, 25, and 50 kPa over a 0.7-5.5 MHz frequency range. A second sample is characterized by attenuation measurements at acoustic pressures ranging from 5 to 75 kPa in steps of 2.5 kPa. Scattering and attenuation coefficients were modeled by integration over the pressure and frequency dependent response of all bubbles located within the non-uniform acoustic characterization beam. For all driving pressures and frequencies employed here, the coefficients could be modeled using a single and unique set of shell parameters confirming that acoustically sorted bubbles provide a uniform acoustic response. Moreover, it is shown that it is crucial to include the pressure distribution of the acoustic characterization beam in the modeling to accurately determine shell parameters of non-linearly oscillating bubbles.

The sensitivity and efficiency in contrast-enhanced ultrasound imaging and therapy can potentially be increased by the use of resonant monodisperse bubbles. However, bubbles of the same size may respond differently to ultrasound due to differences in their phospholipid shell. In an acoustic bubble sorting chip, resonant bubbles can be separated from the polydisperse agent. Here, a sample of acoustically sorted bubbles is characterized by measuring scattering and attenuation simultaneously using narrowband acoustic pulses at peak negative pressures of 10, 25, and 50 kPa over a 0.7-5.5 MHz frequency range. A second sample is characterized by attenuation measurements at acoustic pressures ranging from 5 to 75 kPa in steps of 2.5 kPa. Scattering and attenuation coefficients were modeled by integration over the pressure and frequency dependent response of all bubbles located within the non-uniform acoustic characterization beam. For all driving pressures and frequencies employed here, the coefficients could be modeled using a single and unique set of shell parameters confirming that acoustically sorted bubbles provide a uniform acoustic response. Moreover, it is shown that it is crucial to include the pressure distribution of the acoustic characterization beam in the modeling to accurately determine shell parameters of non-linearly oscillating bubbles.

The sensitivity and efficiency in contrast-enhanced ultrasound imaging and therapy can potentially be increased by the use of resonant monodisperse bubbles. However, bubbles of the same size may respond differently to ultrasound due to differences in their phospholipid shell. In an acoustic bubble sorting chip, resonant bubbles can be separated from the polydisperse agent. Here, a sample of acoustically sorted bubbles is characterized by measuring scattering and attenuation simultaneously using narrowband acoustic pulses at peak negative pressures of 10, 25, and 50 kPa over a 0.7-5.5 MHz frequency range. A second sample is characterized by attenuation measurements at acoustic pressures ranging from 5 to 75 kPa in steps of 2.5 kPa. Scattering and attenuation coefficients were modeled by integration over the pressure and frequency dependent response of all bubbles located within the non-uniform acoustic characterization beam. For all driving pressures and frequencies employed here, the coefficients could be modeled using a single and unique set of shell parameters confirming that acoustically sorted bubbles provide a uniform acoustic response. Moreover, it is shown that it is crucial to include the pressure distribution of the acoustic characterization beam in the modeling to accurately determine shell parameters of non-linearly oscillating bubbles.