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Flow velocity estimation is an important feature in ultrasound imaging. However, in conventional color Doppler imaging, only parallel flow components can be estimated, the velocity information is not simultaneously measured throughout the region of interest (ROI) due to sequential firing of the ultrasound beams, and the size of the ROI is limited under frame rate concerns. On the other hand, ultrafast...
Pulse wave velocity (PWV) is a reliable index of arterial stiffness. To date, reflected pulse wave interference is still a major challenge for regional PWV estimation using ultrasound imaging methods. In this study, a high-resolution Radon transform (HRT) method is proposed to eliminate the reflected wave interferences in PWV estimation.
Displacement estimation is a critical component of elastography. The measurement of sub-resolution displacements relies on high cross-correlation (CC) between repeated collinear RF acquisitions. CCs are degraded by common sources of acoustic noise, such as reverberation clutter, in addition to the displacement of scatterers within the radiation force field. CCs are also degraded spatially across the...
We have recently demonstrated the feasibility of vascular guided wave imaging (VGWI) in non-invasive estimation of bi-plane (i.e., longitudinal and transverse) transmural arterial Young's modulus (ELV, ETV) in tubular phantoms using phase velocity (cph) (Guo et al., ITEC 2016). In this study, we further compare the ETV estimated from the circumferential Lamb type (CLT) wave by VGWI with ETP from the...
The pulse-echo method based on transmission of an ultrasonic pulse and time-of-flight determination of a reflected echo is one of the typical methods of ultrasonic distance measurement. To improve the SNR of the reflected echo, pulse compression using an M-sequence is employed in the pulseecho method. In the case of a moving object, however, the echo is modulated owing to the Doppler effect The Doppler-shifted...
Plane-wave imaging plays a highly significant role o wing to the special demand for high frame rate, however, its po or image quality hinders its application in ultrasound industrie s. Many scholars have attempted to give a wide variety of soluti ons to improve the image quality, however, each of them has li mitations or compromises. In this study, we improve the spatio -temporally smoothed factor...
In recent years, accurate location and characterization of damage has motivated the engineering community to develop several damage identification techniques. Many of the nondestructive evaluations and structural health monitoring techniques are based on the analysis of huge amount of data collected from acousto-ultrasonic sensors. Such analysis is typically a very time-consuming process. Therefore,...
In vivo estimation of attenuation coefficients is useful because of its potential for tissue characterization and relevance in accurate backscatter coefficient estimation. However, current methods based on spectral analysis for ultrasonic attenuation estimation suffer from a severe trade-off between estimation precision and spatial resolution. Recently, the regularized spectral log difference (RSLD)...
The estimation of Ultrasound-Contrast-Agent (UCA) kinetics from Dynamic Contrast-Enhanced Ultrasound (DCE-US) recordings has shown promise to localize prostatic malignancy. In a two-dimensional (2D) approach, UCA dispersion and velocity provide a characterization of the prostate (micro)vasculature with diagnostic value [1]. To this end, the UCA transport kinetics are modelled with strong assumptions...
Cervical spine pathoanatomy is typically evaluated by static radiographs, CT or MRI; however, these modalities are unable to directly measure the dynamic performance of the spine that account for its functionality. We have developed an ultrasound based technique that provides a non-invasive, realtime, quantitative, textitin-vivo image of the C-spine that allows for assessment of the dynamic motion...
To obtain accurate blood flow velocity estimates it is important to remove the clutter signal originating from tissue. Conventionally, the clutter signal has been separated from the blood signal based on the difference of their spectral frequencies. However, this approach is not enough for obtaining vector flow measurements, since the spectra overlaps at high beam-to-flow angles. In this work a distinct...
The technique of non-invasive cortical bone quality assessment using ultrasound axial transmission has attracted considerable attention. Estimating the phase velocity and the attenuation of the absorbing plate will assist the assessment. Among several techniques proposed for these purposes, many employ either a thresholding process or a peak search process. The thresholding process uses the intensity...
In pulse compression using an M-sequence, the M-sequence modulated signal is transmitted and the received signal is correlated with the transmitted signal. However, the M-sequence modulated signal reflected from a moving object is Doppler-shifted. The Doppler-shifted M-sequence modulated signal cannot be correlated with the transmitted signal. Therefore, Doppler velocity estimation from a cyclic M-sequence...
Developing tools to visualize urinary flow dynamics is important, because urinary hydrodynamics is known to have a causal relationship with urethral voiding dysfunction problems. Yet, the design of such an imaging technique is challenging as fine time resolution is essential to track urine passage that can traverse at >2m/s speeds. Previously, we have overcome the time resolvability challenge in...
The Reference Phantom Method can be used to quantify acoustic properties of tissue by compensating for system effects using the average power spectrum from a well-characterized homogeneous medium. Widespread clinical application of the Reference Phantom Method is hindered by the need to scan the reference phantom using the same transducer, system, and system settings as used for scanning the tissue...
Experimental results from volumetric 3-D vector flow measurements using a 62+62 row-column addressed (RCA) array are presented. A plane-by-plane steered transmit sequence and its post processing steps are described for obtaining 3-D vector flow in a volume. A modified version of the transverse oscillation (TO) velocity estimator is used, which exploits the focal lines generated with the tall elements...
Pressure measurements within the chambers of the heart yield critical information for diagnosis and management of cardiac patients (∼92 million Americans), but cardiac catheterization procedure is invasive and expensive. Subharmonic aided pressure estimation (SHAPE) may be able to estimate intra-cardiac pressures noninvasively, if the optimum incident acoustic output (IAO) for SHAPE can be established...
Subharmonic aided pressure estimation (SHAPE) is based on the inverse relationship between the subharmonic amplitude of contrast microbubbles and the ambient pressure. A noninvasive ultrasound based pressure estimation procedure would be a major development in the diagnosis of portal hypertension and less invasive than the current hepatic venous pressure gradient (HVPG) measurement. The hypothesis...
Left intraventricular blood flow follows a range of patterns that are mostly overlooked when using conventional ultrasound Doppler techniques. Vortices, in particular, as a blood redirection mechanism, could provide important information on a patient's cardiovascular health. They are not usually visualized, however, due to the need for 2D velocity vector visualization, and their transient nature,...
Lagrangian carotid strain imaging (LCSI) involves estimation of deformation in the carotid artery due to blood pressure variations under cardiac pulsation. Local strain over a cardiac cycle is tracked, which is computationally intensive. We incur long offline processing times for LCSI which becomes a limiting factor for clinical adoption. We report on the computational speedup obtained for a parallelized...
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