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Flow cytometer plays a key role in cell sorting and analysis. For a higher detection precision, sheath flow is adopted to avoid the turbulent or vortex effect when the cell flowing through a capillary tube during the cell counting in many commercial cytometers. This method works well when the low flow velocity is relatively low. However, in order to have a higher analysis efficiency for clinical laboratories,...
Accurate diagnosis of non-alcoholic steatohepatitis (NASH) is a critical issue in current clinical practice. Non-invasive diagnosis of NASH can be achieved by quantitative ultrasound (QUS), which requires a detailed understanding tissue-specific acoustic microstructure at cellular scale (i.e., 10 μm). Therefore, QUS methods would benefit from the knowledge of the acoustic properties of organelles...
We have studied C-mode and B-mode imaging using high-frequency ultrasonic waves through a thin fiber for direct observation of the microscopic image of tissue. We reported previously that the C-mode images of the tissue on the glass and B-mode image of animal bone placed in water were obtained using a fused quartz fiber as the needle-type ultrasound probe. In this paper, we propose a method for the...
It is widely accepted that cell membrane rupture induced by bubbles oscillating beside the cells is a maj or mechanism of sonoporation; however, elucidation of bubble dynamics by high-speed observation is still important because the behavior is highly dependent on their surrounding conditions. In this study, a new observation chamber was developed. The observation chamber allows observation of bubble-cell...
Acoustic droplet vaporization (ADV) has shown a great potential in extravascular tumor-targeting theranostics. The mechanical perturbations produced during ADV process (e.g. initial volume expansion, cavitation, and movement of the bubble) on the nearby cells could cause cell dysfunction with irreversible cell membrane damage or facilitate drug delivery due to sonoporation. A confocal acousto-optical...
We present a new technique for photoacoustic (PA) image formation, termed ‘F-Mode’, which capitalizes on variations in the power spectrum of PA signals to produce images with object specific contrast. The technique is applied to a PA dataset by calculating the signal power spectrum at each scan location, segmenting it into discrete frequency bands, and then forming an image representing the spatial...
Photoacoustic Microscopy (PAM) offers a unique combination of high contrast from endogenous optical absorbers, and increased penetration to image microvasculature. However, images of the vasculature at increased depth are often corrupted by acoustic reverberation from superficial layers. In this paper, we present an algorithm using dictionary learning to remove the reverberant signal while preserving...
Sub-diffraction imaging, also known as ultrasound localization microscopy, is a novel method that can overcome the fundamental diffraction limit by localizing spatially isolated microbubbles. This method requires the use of a low concentration of microbubbles to ensure that they are spatially isolated. For in vivo microvascular imaging, especially for cancer tissue with high microvascular density,...
Super-resolution ultrasound enables detailed assessment of the fine vascular network by pinpointing individual microbubbles, using ultrasound contrast agents. The fidelity and achieved resolution of this technique is determined by the density of localized microbubbles and their localization accuracy. To obtain high densities, one can evaluate extremely sparse subsets of microbubbles across thousands...
The recent development of ultrafast ultrasound localization microscopy (Errico et al., Nature, 2015) provides new opportunities for imaging the vasculature with sub-diffraction resolution. However, the large number of images to be recorded requires acquisitions lasting several minutes. Therefore, physiological motion far larger than the achievable resolution presents challenges for moving tissues...
Ultrasound localization microscopy has first been demonstrated to overcome the penetration/resolution trade-off [Couture et al IEEE IUS 2011]. Inspired by FPALM in optics and exploiting ultrafast ultrasound imaging, it allowed the reconstruction of a full velocity map of the rat brain vasculature with a micrometric resolution (8μm) [Errico et al. Nature, 2015]. Despite additional successes for tumour...
To understand physiologic state in diseased liver e.g. non-alcoholic steatohepatitis, this study aims to analyze the acoustic impedance (Z) of hepatic cells using a scanning acoustic microscopy (SAM). Ultrasound scattering sources in cells, however, cause the multi-reflection and prevent from analyzing the precious value of Z although it provides the useful information of structure in cells (M. N...
Mobile filters are required to process increasing RF power levels, driven by the need for higher data-rates and improved cell-edge coverage. This results in more demanding filter specifications for loss, rejection, isolation, linearity and reliability, while, at the same time, handset OEMs require smaller filter footprints.
Scanning acoustic microscopy (SAM) is a well-accepted modality for forming quantitative 2D maps of acoustic properties of soft tissues at microscopic scales. In our SAM studies, the sample is raster-scanned (spatial step size of 2 μm) using a 250 MHz transducer resulting in a 3D RF data cube. Each RF signal is processed to obtain, for each spatial location, acoustic parameters, e.g., speed of sound...
Focused ultrasound (FUS) with circulating microbubbles creates transient and reversible permeabilization of vasculatures which provides an essential means to deliver therapeutics and imaging agents, for instance across the BBB. We have previously shown that 3D color Doppler and photoacoustic imaging can monitor BBB disruption (BBBD) in mice. Here we study how changes in NPs size, concentration and...
Cortical bone is an anisotropic material with hierarchical structure whose elastic properties are described at different length scales. At millimeter-scale, the whole set of stiffness tensor can be conveniently measured by resonant ultrasound spectroscopy (RUS). At microscopic-scale, micro-indentation and scanning acoustic microscopy are often used to quantify tissue matrix elastic properties. However,...
Ultrafast Ultrasound Localization Microscopy (uULM, Couture et al. IEEE IUS 2011) takes inspiration from the FPALM technique applied in optics as it relies on the detection of single scatters localized at a resolution below the half-wavelength theoretical limit. The tracking of microbubbles injected in the blood stream lead to unprecedented resolution for in-vivo imaging of the rat brain (Errico et...
Introduced recently [Couture et al., IEEE IUS 2011], ultrasound super-resolution techniques such as ultrafast Ultrasound Localization Microscopy (uULM) surpasses the diffraction-limit and reach resolution an order of magnitude better than the diffraction limit resolution. We previously exploited uULM to achieve resolution of 8 μm over a depth of 12 mm in the rat brain vasculature [Errico et al, Nature...
Ferroelectric polymers like polyvinylidenefluoride (PVDF) and its copolymer with trifluoroethylene [P(VDF-TrFE)] are widely used in sensor and transducer applications. Good acoustic match to many materials (e.g. water, polymers, and human tissue) and high chemical stability make these materials suitable for ultrasonic applications, especially in the high frequency end (20 MHz-1 GHz). The current work...
A high-speed observation system for sonoporation study was improved for observation of bubble and cell dynamics under ultrasound exposure from a lateral direction. The effect of the presence of a scaffold mimicking an in vivo situation on the dynamics was investigated to study the mechanisms by which bubbles cause cell membrane damage. Observations showed that the stiffness of the scaffold has a significant...
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