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Controlling cell functions for drug development and therapeutic purposes has been an important method in clinic to treat critical diseases such as cancer and neurodegenerative diseases. Modulation of cancer cells and finding specific mutations in cancer are methods to investigate mechanism of outbreak of cancer. The advancement in molecular biology introduced tools to precisely edit genome of cells...
Previous study has demonstrated that pulsed HIFU with tens of microseconds pulse duration (PD) and 10kHz PRF is effective for cavitation generation. Meanwhile, with the assistance of PFC nanodroplets, cavitation can be further enhanced. Despite of higher efficiency, we also need cavitation to be precisely controlled and confined for sake of therapeutic safety, especially during the implementation...
Histotripsy uses high-pressure, microsecond-length pulses to generate cavitation microbubbles to fractionate targeted tissue. After the collapse of a cavitation cloud, remnant microbubbles can persist for a second or longer before passively dissolving. These bubbles can act as seed nuclei for subsequent cavitation events reducing treatment efficiency because the nuclei are not well distributed through...
Noninvasive electrical brain imaging in humans often suffers from poor spatial resolution due to the uncertain spread of electric fields through the head. To overcome this limitation, we propose 4D transcranial acoustoelectric brain imaging (tABI) for mapping current densities at a spatial resolution confined to the ultrasound (US) focus. Acoustoelectric (AE) imaging exploits an interaction between...
Ultrasonic standing waves (USWs) particle sorting has shown great potential to develop diverse applications in biotechnology and medical research due to its ability to offer non-contact, label-free particle manipulation. Currently, most reported on-chip acoustic particle sorters rely on high Q-value materials and elaborate geometry designs, which make these devices not easy to build and unsuited for...
High-frequency ultrasound (>20 MHz) imaging has gained widespread attention due to its high spatial resolution being useful for basic cardiovascular and cancer research involving small animals. The sampling rate of the analog-to-digital converter in a high-frequency ultrasound system usually needs to be higher than 120-MHz to satisfy the Nyquist requirement. However, the sampling rate is typically...
Contrast echocardiography (CE) ultrasound with microbubble contrast agents have significantly advanced our capability in assessing cardiac function. However in conventional CE techniques with line by line scanning, the frame rate is limited to tens of frames per second, making it difficult to track the fast flow within cardiac chamber. Recent research in high frame-rate (HFR) ultrasound have shown...
The concept of contrast imaging using microbubble superharmonic signals was introduced in 2002[1]. A number of implementations with detection above 10 MHz have been reported, in particular by our group using a 25–30 MHz single element receive transducer concentric with a low 2–4 MHz transmit ring[2]. In the present work, the implementation of dual frequency (DF) imaging on a Vevo 2100 (VisualSonics,...
Recent studies suggest that microbubbles based contrast enhanced intravascular ultrasound (CE-IVUS) for vasa vasorum assessment is promising in the identification of vulnerable plaques. However, conventional ultrasound is not suitable for imaging modality which demands up to 5th order harmonics for a receiver. To ensure the imaging performance, high-frequency broadband micromachined 1–3 composites...
Lipid-stabilized microbubbles are used in various clinical ultrasound (US) applications such as diagnostics imaging and therapeutics. The characteristics of the microbubbles such as size, shell material, and US frequency dictate the acoustic response of these microbubbles. Therefore, monodispersed microbubbles with the length-scale (1–7 μm in diameter) relevant to the biomedical ultrasound applications...
Currently there are two main categories of adaptive beamforming applied to medical ultrasound imaging: minimum-variance-related beamforming(MV) and coherence-factor-related beamforming (CF), both of which have been applied to suppress side/granting lobe and clutter for plane-wave imaging. Unfortunately, due to low SNR/SINR, the resulting images may suffer from deficiencies: deteriorated speckle pattern,...
3D diverging wave compounding (DWC) was recently demonstrated to be capable of providing high-frame-rate imaging, but at the risk of introducing motion artifacts. As an alternative, a hybrid beamforming approach combining the features of DWC and multi-line-transmit (MLT) beamforming was proposed (i.e., multi-plane-transmit, MPT), showing some superiority when compared with 3D DWC [1]. However, in...
Perfluorocarbon nanodroplets (PFCnDs) are emerging ultrasound (US) contrast agents that seek to enable contrast-enhanced imaging of extravascular spaces and offer increased biological stability and circulation times compared to traditional microbubbles (MBs). However, rigorous studies have not analyzed the impact of shell composition on PFCnDs. In particular, lipid-shell PFCnD formulations borrow...
Arrhythmias can be treated by ablating the heart tissue in the regions of abnormal conduction, e.g. activating too early or with a different speed. The key of the treatment then lies in the location of these areas. In current clinical practice, 3-D electroanatomic maps can be created during the procedure by probing the heart with a specific catheter. However, it is a time-consuming and invasive procedure...
Ultrasonic (US) brain stimulation, has been demonstrated to noninvasively alter neuron activity in animals and humans. Capable of non-invasive transmission trough skull with fine focal size (∼mm), it is an encouraging means and a good alternative to existing stimulating strategies. However, the bio-effects of US are diverse and thus it is crucial to develop precise neuron control strategies for later...
Super-resolution ultrasound has potential for visualisation of microvasculature1. Techniques that localise isolated bubble signals first require detection algorithms to separate the bubble and tissue response. Resolution of the tortuous microvasculature requires localisations with accuracy on the micron scale. Tumour microvasculature blood velocities are <1mm/s, and even for vessel diameters approaching...
Renal parenchyma is strongly anisotropic; mechanical properties differ along versus across nephron alignment. In this work, the feasibility of interrogating such directional differences in mechanical property using ARFI is investigated. We hypothesize that: 1) the ratio of ARFI peak displacements (PDs) achieved with the long axis of an asymmetrical ARF PSF oriented along versus across nephron alignment...
High frame-rate contrast enhanced echocardiography (HFR CE), based on pulse inversion (PI) and diverging wave transmission, was recently proposed for improving the image contrast over standard contrast enhanced ultrasound (CEUS) with focused transmission [M. Toulemonde, IUS 2016]. While it has great potential for improved quantification of myocardium perfusion, it is not clear as whether the stability...
Clinical translation of targeted contrast agents for molecular imaging of disease precludes the use of the biotin-avidin cross linking strategy due to the immunogenicity of avidin. Our objective was to cross link targeting ligands to ultrasound contrast using non-immunogenic covalent chemistry, and to validate the resulting targeted contrast agents using a binding assay to cultured cells.
Microbubbles (MBs) excited by ultrasound (Us) are used as contrast agents for the detection of blood vessels. MBs can also be used to enhance drug delivery. However, the usage of MBs is limited to the blood pool due to their large size; where detection of biomarkers on tumor cells and effective drug delivery, requires MBs to reach the tumor tissue outside of the vasculature.
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