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Treatment of renal cell carcinoma (RCC) using ablation techniques is becoming increasingly common as a means for preserving renal function in poor surgical candidates. Despite concerns related to renal insufficiency, which is common in patients with renal disease, the current standard for imaging surveillance following ablation remains contrast-enhanced CT or MRI. Contrast-enhanced ultrasound (CEUS)...
Subharmonic emission from gas-filled microbubbles is of interest because it can improve the sensitivity of contrast-enhanced ultrasound imaging. However, subharmonic emission exhibits a delay between the insonification and its generation. In this study, we investigated the impact of applied acoustic pressure and microbubbles gas composition on the time dependent emission of subharmonics of five phospholipid...
Growing demand for bedside medical imaging with increased ease of access has motivated development of more cost-effective ultrasound systems. Multimodal imaging techniques such as Microwave-induced Thermoacoustic (TA) tomography can simplify system design by providing enhanced imaging contrast. The introduction of continuous-wave (CW) TA has made this technique more cost-effective by reducing device...
Drilled shaft is an important substructure foundation in building construction. A drilled shaft needs to be placed precisely in high accuracy and satisfy the diameter precision requirement. In order to measure the verticality and the diameter of a shaft, the M-superimposed Gaussian Echoes Model (GEM) is used to estimate the time of flight (TOF) of ultrasound. Compared to the conventional threshold...
In this research, piezoelectric micromachined ultrasonic transducer (pMUT) array was used for stimulation of mechanosensitive channel of HEK293T cells. The fabricated pMUT array was made by microelectromechanical system (MEMS) technology such as photo process, etching, sputtering, and sol-gel method. The resonance frequency and acoustic positive peak pressure were 2.07 MHz and 3.94 kPa, respectively...
The advent of ultrafast ultrasound imaging proved beneficial for capturing transient flow patterns which was never readily achievable before. Velocity estimation methods based on 2D block-matching outperform Doppler based methods by offering higher frame rate with the cost of increased uncertainty in presence of out-of-plane motion as a result of turbulent flow.
Prototypes of a PZT-based ultrasound needle-actuating device have shown the ability to reduce needle penetration force and enhance needle visibility during needle insertion for tissue biopsy and regional anaesthesia. Further demand for smaller devices and the need for high performance transducers has motivated the investigation of a different configuration of needle actuation transducer, utilizing...
Improving the ultrasound image contrast ratio (CR) and contrast to noise ratio (CNR) has many clinical advantages. Breast cancer detection is one example. Anechoic cysts which fill with clutter noise can be easily misinterpreted and classified as malignant lesions instead of benign. Beamforming techniques contribute to off-axis side lobes and clutter. These two side effects inherent in beamforming...
Plane-wave (PW) imaging achieves narrow lateral beam width using boxcar apodization but at the expense of high side-lobes, which degrade the performance of vascular elastography. The goal of this study was to investigate various imaging techniques for improving the performance of PW imaging. More specifically, we evaluated the quality of elastograms produced with: (1) fixed apodization beamforming...
In medical ultrasound imaging, Signal-to-noise ratio (SNR) is an important factor for imaging quality. Coded excitation methods have been widely used such as Golay codes and Barker codes to achieve higher SNR without degradation of axial resolution. The improvement of SNR is determined by code length. However, because conventional Golay codes and Barker codes are limited to specific known sequences,...
Photoacoustic imaging is used to differentiate between tissue types based on light absorption. Different structures, such as vascular density of capillaries in human tissue, can be analysed and provide diagnostic information to detect early stage breast cancer. Delay and sum (DAS) beamforming is the traditional method to reconstruct photoacoustic images. However, for structures located deep in the...
We present an acoustic interference microscope. This device employs a continuous Tx signal and the time-of-flight of the echoes are calculated from interference between incident and reflected waves by an inverse Fourier transform. Using a 175 MHz focused transducer we measured a B-scan across a 5 µm silicon step sample with both the acoustic interference and a conventional ultrasound microscope. The...
Targeted microbubbles are currently used as ultrasound contrast agents in pre-clinical studies to visualize disease markers present on the blood vessel endothelium. Rapid clinical translation of targeted microbubble imaging requires a minimization of the diagnostically effective microbubble dose. In this study, we demonstrate an imaging method that improves signal-to-noise ratio (SNR) for microbubble...
We have been studying experimental methods using cultured cardiomyocytes to evaluate the effect of short-pulsed ultrasound for generating disruption in pulsation such as premature contractions. In this study, we focused on the effect of ultrasound pulses with longer duration for a basic study on the safety of acoustic radiation force impulse (ARFI) imaging. Cardiomyocytes isolated from neonatal rats...
A 360° fully functional endoscopic ultrasound radial array has been fabricated and evaluated. Transducer was specially designed to match the endoscope structure, which has a 10.5mm outer diameter, a 7.5mm inner diameter and a system connecting cable measuring 3.5m. Considering the size limitation in endoscopic application and transducer fabrication capability, two transducer designs with 192 and 252...
In ultrasound shear wave elastography (SWE), phase aberration can impact both push and tracking beams. From the literature, however, it is not clear whether performance loss in tissue stiffness reconstruction should be attributed more to push or tracking. To answer this question, we developed a research prototype based on a commercial ultrasound scanner EPIQ (Philips Healthcare, Andover, MA, USA)...
In order to improve efficiency and security in heat applications during hyperthermia, it is important to monitor tissue temperature during treatments. Photoacoustic (PA) pressure wave amplitude has a temperature dependence given by the Gruenesein parameter. Therefore, changes in photoacoustic signal amplitude carry information about temperature variation in tissue. Therefore, PA has been proposed...
The predominant causes of stroke and transient ischemic attacks is growth of atherosclerotic plaque in the carotid artery. To aid in diagnosis of these vulnerable plaques, there exists a clinical need for a point-of-care tool for determining plaque composition in carotid arteries. Ultrasound backscatter RF data was collected from 20 human subjects scheduled for a carotid endarterectomy (CEA). The...
We are aiming to develop a puncture-type ultrasound microscope by which less invasive settled diagnosis can be executed. To provide in vivo high-resolution imaging of a tumor, we need to scan high frequency ultrasound by rotating an acoustic mirror or an ultrasound oscillator at the tip of a probe. As a driving source device for rotating those, we can use our miniature ultrasonic motor. To narrow...
Concrete is composed of sands, aggregates, cement and other fine powders that are dispersed in water to produce a chemical reaction, called hydration, responsible of the concrete hardening. The monitoring of the growth of compressive strength during hydration and its measurement at the end of the reaction is fundamental for evaluating the concrete quality. Currently the strength is measured in laboratory...
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