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Endoscopy and colonoscopy are the clinically recognised standards for imaging and diagnosis of diseases of the gastrointestinal (GI) tract. While 'scope-based approaches combine optical and ultrasound imaging to allow both imaging of the surface and full thickness of the bowel wall, they are limited in their ability to access the full length of the GI tract particularly the small bowel. Wireless video...
Histotripsy is considered a non-invasive therapeutic modality capable of mechanically fractionating tissue using cavitation bubbles induced by high intensity focused ultrasound pulses. Histotripsy-induced cavitation region over relatively large focal volume is effective in treating sizable lesion, while compromising its treatment precision. We demonstrate high-precision cavitation treatment using...
With the ongoing drive to integrate more functionality and processing power on the same semiconductor area, the device structures have become 3D. Such structures, like FinFETs and their successors GAA nanowire FETs, bring on new challenges to measure their geometry and material properties non-destructively at the nanometer scale. Photo Thermal Acoustic Imaging (PTAI) is a potential inspection method...
Ultrasound (US) is an ideal imaging modality used in medical practice: it is portable, has no known bio-effects and produces images with excellent resolution. Despite these advantages, MRI and CT are dominant modalities used for most medical imaging, while accepting much higher cost and health risks. US is acquired with hand held transducers dependent on operator applied pressure and angle plane selection...
Optically triggered perfluorohexane nanodroplets (PFHnDs) can repeatedly vaporize and recondense, providing photoacoustic (PA) and blinking ultrasound (US) signals in response to pulsed laser irradiation. This property of PFHnDs has led to the development of various US imaging modes, including super-resolution and background-free contrast-enhanced imaging. However, to utilize the full potential of...
EUS is performed with radial imaging perpendicular to the endoscope shaft, and lateral imaging parallel to the shaft and biopsy channel. Radial imaging is preferred for some diagnostic and staging purpose because of ease of use as well as the production of a full 360-degree field of view. For operation smoothly and safety, the smaller external diameter (less than 11mm), the higher optical and ultrasonic...
To explore the extravascular space, sub-micron phase-change droplets show widespread interest in medical imaging and therapy with various modalities, such as ultrasound and photoacoustic. Existing studies (Wilson 2012, Wei 2014) on such dual-modality contrast agents have demonstrated the generation of both optical and ultrasound contrast after optical activation. However these studies did not explore...
Investigation of the complex intra-ventricular flow patterns in the left ventricle (LV) remains a challenge in clinical ultrasound. Echo-particle image velocimetry (ePIV) is able to estimate 2D flow from 2D images, but it is known to underestimate the high velocity flows present during the filling and ejection periods of the cardiac cycle[1], [2]. High frame rate (HFR) ultrasound imaging has been...
Rupture of an atherosclerotic plaque in the carotid artery is one of the main causes of stroke and stroke-induced death. Currently, to prevent this risk, endarterectomy is performed based on the stenosis grade assessed with Duplex ultrasound (US). However, plaque composition, e.g. presence of lipids and hemorrhages, is a more important factor of rupture risk than stenosis. The optical absorption of...
Photoacoustic (PA) imaging is an emerging molecular imaging modality. Image contrast, however, strongly decreases with depth due to light attenuation in tissue. Recently, PA phase-change contrast agents (PCCAs) have been proposed as alternative PA agents because the rapid expansion from droplet vaporization provides contrast orders of magnitude higher than that of conventional PA agents. Current PA...
The abnormal vasculature of tumor and the resulting abnormal microenvironment is a major barrier to optimal chemotherapeutic drug delivery. It is well known that ultrasound (US) can increase the permeability of the tumor vessel walls and enhance the accumulation of anticancer drugs. Reconstituted high density lipoproteins (rHDL) nanoparticles (NPs) allow selective delivery of anticancer agents to...
Conventionally, images are normally displayed by amplitude or intensity information. However, acoustic images are different from optical images. The frequency information is significantly important in acoustic images since the frequency information can reflect the object characteristics (surface profiles, structures hidden under surfaces, and material properties of objects). In this study, we propose...
In this study, we developed an imaging device for preclinical and clinical application using photoacoustic effect. The photoacoustic effect is to make ultrasound images using light as its name illustrates. Light irradiated in a short time (nano seconds) is absorbed by the tissue, and the local pressure is generated by the thermo-elastic expansion. The photoacoustic effect is a safe method of imaging...
One of the main advantages of photoacoustic (PA) microscopy is its ability to generate high-resolution maps of vasculature due to strong endogenous absorption. In contrast the optical absorption of the gross anatomy surrounding the vasculature is negligible, and it is thus not readily imaged using PA. We have previously reported on a new imaging technique, termed Photoacoustic Radiometry (PAR), which...
Transparent transducers are desired in the applications where optics and acoustics are combined, such as integrating ultrasound sensing or parametric arrays for directional sound in display, combined optical and acoustical microparticle manipulation, and backward-mode photoacoustic imaging. Some piezoelectric materials, e.g., PVDF, LNO, and PLZT, have been investigated for such applications. Besides,...
Intravascular photoacoustic (IVPA) imaging is being developed to improve and guide treatment of atherosclerotic vulnerable plaques. While lipid has been successfully imaged, current studies have not determined how many or which optical wavelength(s) will accurately characterize atherosclerotic plaques. We leverage Monte Carlo (MC) optical modeling to determine the optimal dual-wavelength combination...
Epi-optoacoustic (OA) imaging allows flexible clinical use, but out-of-plane and echo clutter from strong OA sources limits contrast. In localized vibration tagging (LOVIT), a focused ultrasonic pushing beam creates transient localized displacement and thus a signal phase shift. Subtraction of OA acquisitions before and at the peak displacement highlights signal from the focus and eliminates out-of-plane...
The maximum amplitude projection (MAP) technique is the gold standard for image formation in photoacoustic (PA) microscopy. While the technique provides high-resolution spatial maps of optical absorption, it neglects the abundance of information encoded in the frequency domain of the broadband PA signals. In this work, we present a new technique for PA image formation, termed ‘F-Mode’, which capitalizes...
A hydrophone scanning method is gold standard for the ultrasound filed measurement. However, the hydrophone scanning is time consuming especially for the three-dimensional measurement. On the other hand, two-dimensional data can be acquired simultaneously by an optical measurement method using a camera. In this study, the optical phase contrast method was used to measure a three-dimensional pressure...
Photoacoustic (PA) imaging is an emerging technique used with ultrasound imaging to provide molecular specificity. Even with contrast agents, PA imaging suffers from poor penetration depth due to strong light attenuation in tissue. Recently, Phase-change contrast agents (PCCAs) have been proposed as an alternative agent since volume expansion during the vaporization process results in significantly...
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